I hate how British people get all mortally offended by stuff but they don't just come out and say it, they'll just act passive aggressive or bitch behind your back instead.
Stupid rules like not giving money at weddings and poems asking for money is tacky - who honestly gives a shit?
Endless moaning - I do it too but my husband doesn't understand why. His culture is very much "put up or shut up" which I prefer these days.
Pretending class doesn't exist. Middle class people getting all huffy about the word "chav" when every single working class person uses it with impunity to mean someone who acts like an outrageous chump.
Moaning about immigrants, particularly because the reason we're a wealthy country that people want to immigrate to is because we went around colonising everywhere
The fact that people can't see that we are a bit shit as a country these days. Take coronavirus as an example - people can't accept that the reason many Asian countries did a better job of stopping the spread of it isn't culture or SARS or weather or food, it's because the people actually hold their governments accountable and the governments actually give a modicum of shit about the people. Our government couldn't care less and yet people continue to line up to rim Boris Johnson. Or worse, just shrug their shoulders and say "meh that's just how it is".
The fact that so many English people are completely ignorant about Scotland, NI and Wales.
There are so many good things about the UK but we are declining fast.