So I agree with what you are saying, but I think you (and many people) misunderstand what a politician's job is for. They are there to deliver, and simplify messages to try and get people on-board with whatever idea they are campaigning for. This may mean over-simplifying a complex system, or "bending the truth" (a good politician can do this in the face of accusations about lying and claim that what they are saying is true if you look at the data in a certain sort of way). A politician is not your friend...again none of this is surprising.
> I didn't expect Brexit to be this bad,
I think we have different ideas of what "bad" is. There are understandable difficulties, but black-swan events in recent years have completely overshadowed any damage that Brexit may be causing. COVID-19 is "bad" in my books. Chinese/Russian influences are "bad". Also see chip shortages, global supply chain issues, etc. Arguments about fishing are not - unless you are one of the small number of people affected by this...again on the scale of a country I'm not convinced.