I don't think Mumsnet has a big problem with bots. If Mumsnet is the only place you post, and you're not used to having your views challenged, I can see why it's tempting to think so. But if you spend five minutes on any other platform, it's easy to spot the bots. They're really not as sophisticated as people make them out to be.
The suspicious posters we get on Mumsnet tend to be - in my view - journalists looking for something they can build into a story, or else just plain old market research. The big draw is to be able to sell us stuff, not influence how we think on politics.
You can tell the bot situation is not actually bad on here because we haven't been overtaken by the same Lindsay Clancy and Cornell 7 mania that has the rest of the internet in its grip. Both seem like very astroturfed stories to me, designed to create a backlash against women / feminism ahead of the American elections. (To be clear, I think the stories are real but the push to make them a huge public conversation has been artificial, and highly suspect.)
By contrast, conversations about Reform and immigration seem pretty in line with the views of real people I've spoken to. I think many "left-leaning" Mumsnetters would be surprised to find out how many of their peers hold such views in secret. The sudden uptick of "new" posters in these threads has always felt more like good old fashioned name-changing to me.