Most anything that is US-centric, like US-only news or US-only politics. Mainly 2 reasons:
These threads are usually filled with heated, badly-moderated, frustrating discussions that lead nowhere.
I am not american, so I cannot even vote or affect things over there in any way, which just makes hearing about the chaotic state of things even more frustrating.
Thus I simply elect not to see those posts at all.
I also block most meme communities, since they otherwise fill the All feed. I can easily just go on incognito/log out to view the all feed with memes if I want a laugh (it’s not that I dislike memes in general).