I'm WOC and have been on MN for years. I'm also working class (lived on disability benefits for years) and middle aged. I consider myself a second wave feminist, am strongly GC, and have been involved in women's rights since the 80s.
Yes, white feminism is a huge problem IMO. My personal definition of "white feminism" is a) women who claim to be feminists yet actively abuse women for no reason other than the colour of their skin; b) women who exploit feminist principles as a way to promote or condone or dismiss racism (for example, expecting black women to shut up about their own experiences on the grounds they are "being divisive"; advocating supporting far right wing politicians including those who are known to hold white supremacist beliefs on the grounds that they are anti-trans; being against anti-racism/intersectionality/wokeness on the grounds that people who are for those things are often pro-trans); and c; men and women who refuse to acknowledge that black women are treated differently by society than white women and either turning a blind eye to racism or actively defending or dismissing it.
Mumsnet has a serious problem with racism, of varying degrees. On one end of the scale are posters who just don't "see" racism and think black women are just making a lot of fuss about nothing. Posters who think racism means actively hating black people, and anything other than outright hate isn't racist. Then you have posters who seem to have an agenda to dismiss and deny racism (while simultaneously talking about how serious anti-white racism is). Posters who hold black people to a different standard. Posters who find it funny to start goady threads about golliwogs or how their toddler said "mummy that man looks like he's made of chocolate!" on the bus. Posters who are fine with black people as long as they behave in a certain way but get upset if they start being "uppity" or "thuggish." Posters who think it's fine to call black people "uppity" or "thugs." Posters who think it's fine to call black people "n*gger." All the way through to a small number of posters who really actively have a violent loathing for black people, like the mere sight of a black person sends them into a fury of rage.
Here are some examples of racism I've personally experienced or witnessed on Mumsnet:
*Constantly being told racism doesn't exist, or "but what about anti-white racism", and having my own and others' personal experiences dismissed or disbelieved. For example, I once posted saying I was upset because I'd witnessed someone say something really racist, and got probably four or five comments saying "well we can't judge because we don't have the other person's side of the story" or "we only have your word that this happened." Like their default was racism-denial.
*Being active on a long thread about racism without revealing that I'm WOC and basically being treated okay by other posters, then disclosing that I'm WOC and immediately witnessing the tone and way I'm treated do a total 180. Like 20 pages of other posters politely disagreeing but without any personal insults, then suddenly the second I say "well actually I'm biracial" I suddenly get a wave of really nasty personal abuse, literally get called stupid, thick, angry, aggressive "cunt", bitch, and generally be treated with far more hostility.
Making a post saying "well actually I'm biracial and I think..." and the very next post after mine was something like "well I just think it's hypocritical that black people are allowed to say NR and I'm not." Except she did not use asterixis, she wrote the word out in full, and yes the N word was typed in all caps. It didn't even make sense in context since no one had even mentioned the N word before, she basically changed the subject because she obviously desperately wanted to engineer a situation where she could scream "NGGER" at a biracial poster. Literally, her first reaction to seeing someone say "I'm biracial" was to immediately scream the N word at them.
*Accidentally posting the acronym "BIPOC" once because I'd been editing documents for an American company all day (it was something like "I don't have a problem with BIPOC actors playing Shakespearean roles"), apologising for using it, and coming back to three pages of outraged posts about how I was being controlling and trying to dictate what terminology people should use and posters literally saying "how dare froggy try to force us to say BIPOC", as well as posts calling me stupid and accusing me of engaging in "American identity politics."
*Having two separate usernames, under one username I'm "out" as biracial, the other one I'm not. People always assume the later username belongs to someone white and I get treated totally differently when I use that username, even though I post the same content in the same style. Other non-white posters have told me they've experienced the same thing. For example posts under my biracial username are much more heavily policed. If I make a grammatical error or typo, it'll be jumped on. Everything from snide comments like "I think you meant 'were' and not 'we're', are you sure you went to university?" for what's obviously an autocorrect error. Or posters ganging up to gleefully crow "isn't it sad that froggy is so stupid"/"yes poor thick froggy really isn't very bright, is she?" I've been on threads where I've been roundly attacked over the tiniest SPAG error, then seen posts like "ppl shuld leave Wills and kate alone there great" (or even posts written in barely comprehensible text speak) and no one says a word.
*Witnessing the extreme abuse and hostility over the mere suggestion that MN should have a section for black women, which was so bad it required police action. Some Mumsnetters were so angry a black woman requested a Black Mumsnetter section they even photoshopped a fake PM to try to get her banned.
*So many goady threads about racial issues, like those endless stupid golliwog threads.
*Threads about anything to do with racism are always full of posters who seem desperate to say that racism doesn't exist and to generally do their best to dismiss, condescend to and undermine BAME posters.
*Black women constantly being told they should be nice and not be aggressive or accusatory because it'll make white people feel defensive and therefore they'll stop caring about racism, and trying to act like "angry black people" are to blame for forcing white people to be racist. Which is exactly the same tactic men have used on women for decades, blaming women for being aggressive and acting like "gee whiz we'd have been happy to give women rights but some of you had to act all angry and get our backs up, so now we won't, see how this is all your fault?"
*Clear double standards along racial lines. For example the threads about the BLM protests were overwhelmingly hostile towards the protestors and contained racially coded language like "thugs". But a week later a thread about the Far Right protest, which was attended by protestors visibly displaying Nazi imagery and doing the Sieg Heil, was noticeably far less negative and and the general attitude was "they are just defending their right to free speech." The BLM protestors were widely accused of spreading Covid yet these accusations were largely absent from the Neo Nazi protest threads. That's just one example of hundreds.
*People making false analogies, like insisting on comparing wealthy upper class black women with poor working class white women in an attempt to prove that white privilege does not exist. Which doesn't even make sense since black people statistically have lower incomes and are much more likely to live in poverty than white people. Do people really believe that "white privilege" means "every single white person is more privileged than every single black person"? Because that is simply not what it means. The definition of white privilege is that white people do not face the additional barrier of racism on top of whatever barriers they face. When discussing white privilege, you have to compare like for like. Compare two working class kids from the same village with the same income level, one white and one black. Who has it worse?