Great post. I'm frequently reminded that 40k people is so much more than it seems as I consistently encounter users who have been here and quite active for 3 years and yet I don't recognize them.
That ban from c/Europe is a badge of honor in my book. One of the nice things about the modlog is that anyone can quickly verify whether bans or comment removals are justified according to their own perspective. It shouldn't always be as necessary as it currently is, but with people on Lemmy constantly throwing around accusations of bigotry, nazism, genocide denial, etc, its quite useful to be able to quickly view a user's moderation history. Honestly that might be the most useful feature that Lemmy has, aside from the ability to federate.
However, I do have one minor quibble with your post.
for me this was quite a shocking confirmation of the intolerance of a certain section of the (mainly US) left.
To ascribe your banning from a European community on a European server because of an opinion on a European situation to the US left is quite unreasonable. Also, the mod who banned you appears to be German. This is one of my pet peeves about Lemmy, that Americans always seem to take collateral damage in the most random threads lol. The Lemmy user base is significantly more international than the reddit user base in my experience, and thus the anti-American attitudes that seem quite common outside of the US are frequently exhibited here.
I don't know that there's anything that can be done about it, but I do know that it's unproductive to blame Americans from the outside looking in. I mean it's unproductive to blame average people for the actions of their government anyway, but it's especially annoying coming from people who don't even live here and often lack a lot of context and empathy with their angry rants. None of this applies to you personally btw, but I'm just saying it for the record.
Pot, meet kettle.