I just block a lot of communities like that. It’s easy in the Voyager app to do this on Lemmy. I also have some filters set up for some of the common words that are used in the doom and gloom posts like what you’re talking about.
It helps out a lot to decrease a lot of the overly negative stuff.
If you find yourself wanting some of it back, maybe you could create a second account that you could log into as you feel it is needed? Voyager allows me to switch between accounts very easily. Or it did, I haven’t had a secondary account in some time, but I did have that function last time I needed it.