I did not have that 3 weeks ago though, and they're not 500s - at least they're not displayed as that. I get pages like this one: https://fedia.io/ecv/7319083/-1
The main thing I experience since the CDN update is that voting often ends up in an error page, similar to how adding comments sometimes directs you to a secondary page (luckily with the comment intact). Going back and trying to vote again may or may not work.
You don't search for hashtags on a content aggregator like this (Lemmy itself didn't even support hashtags until very recently), but for communities / magazines that fit your needs that you subscribe to for a more personalized feed (I'd use external search tools to find communities though, as mbin's magazine search can only find what's already federated) - or just browse /all and let whatever is federated hit you.
I'm not sure where the guys are right now or if you still having that issue but it is likely related to the CDN news from a few days ago, which seems to be the cause for some other issues too.
Did this break federation with lemmynsfw? I just noticed a lack of certain posts on /all, and after double checking it seems there hasn't been anything federated for 4 days. https://fedia.io/d/lemmynsfw.com/
You generally seem to need to have at least 1 account from that instance subscribed to your magazine for federation to kick in (which then still can take a bit of time). Same works the other way around. The unfortunate thing is that you kinda have to use external community / magazine indexers to search for them, unless you know the exact name & instance domain they're in, since a search won't find non indexed ones by itself.
Imo one of the largest issues regarding the fediverse.
That makes no sense to me. Imagine blocking users would work the same way and it would just remove links to their profile, but not the stuff the account posts.
It definitely does not block threads from those instances showing up. For example I have lemmy.ml blocked that way and I still get the occasional lemmy.ml threads pop up and have to manually block all the different communities on that instance.