I actually think in many cases it's more about perceived British values than ethnicity. However, obviously many people from other cultures are non white by default.
There are absolutely loads of non white Britons that are extremely popular with laddish working class men. Look at boxing, for example. Anthony Joshua, Prince Naseem, Daniel Dubois, Frank Bruno, Nigel Benn, Chris Eubank, Amir Khan, Hamzah Sheeraz, Lennox Lewis, David Haye, etc, etc. All working class heroes.
Same with football. And then you have loads of comedians like Lenny Henry, Michael Dapaah (Big Shaq), Sasha Baron Cohen (Ali G), etc. That's just scratching the surface. You've also got musicians like Stormzy, Dizzee Rascal, Miss Dynamite etc amongst many others who are extremely popular with working class youths.
I think it's actually quite rare for anybody outside of the hardcore BNP members to have an issue with non white brits. These individuals aren't remotely big enough in numbers to account for all the support that Reform are getting.
I think a lot of people moaning about perceived 'racists' haven't yet clocked their own problematic views whereby they lump all non white people into the same category. Even when talking about fellow Muslims/Sikhs my workmates will differentiate between somebody born here and 'a freshy' (their words not mine, and not always meant in a derogatory fashion).
Most people wouldn't class an economic migrant fresh off a boat in the same category as somebody like Amir Khan yet a lot of people on the left seem to lump them all together. That's why many can't understand that it's certain cultures that are usually the perceived issue with their ethnicity being a secondary factor.
Many nationalistic people have no issue with non white people that live by our societal code, in the same way they also support British females despite being stereotyped as sexists. Like how loads of blokes are big fans of the Lionesses and Dakota Ditcheva (who seems to have far more male than female supporters).
People don't generally have issues with non white people who share our values. It's those that try and set up their own judicial systems and extend their abuse to the women and children of the countries that take them in that people are getting pissed off with.