I can't for a moment pretend to know anything about politics in the UK. But across the pond, many are dissatisfied with both Democratic and Republican politicians - like you, they are unhappy with the status quo.
That said, voicing support for a radical right wing politician like Trump - a demagogue, grifter and abhorrent person who cares only about himself - a convicted felon, a racist, a nationalist, a con-man, a liar, a misogynist, a fascist, a scoundrel... well, if you support such - you're rightly labeled as a far-right fascist nationalist.
Personally, I'm a centrist - and I very much liked Biden's term in office. And in my opinion he was a great president.
I get that you may disagree - and would support some other candidate - but if you support Trump - then I'm going to go batshit crazy on you and for good reason. Trump is a fascist and wants supreme power - and he's actively trying to achieve this goal. If you support Trump - you are either OK with fascism, or are badly mistaken in what he stands for.