Soon ^tm
Its in .19, the next release.
Don’t worry, youll be able to block hexbear and lemmygrad shortly.
The instance blocking in .19 only blocks posts from an instance, not comments.
Certain apps offer this feature but lemmy itself doesn’t yet, I believe they’re working on it but had some issues implementing it
unfortunately, be aware that this feature is broken on some apps, such as clearing the instance blocklist whenever the app is restarted, rendering it basically useless.
I also wouldn’t mind filtering posts from users belonging to certain instances. But maybe blocking instances will be enough.
Connect app has this
You can with kbin, and I think something was said about it in the upcoming lemmy release.
Kbin’s instance blocking didn’t seem to be working for a while, instead it blocked users of instances at random (a few times I’ve seen a thread from a blocked instance but none of the comments from said instance show up).
It might be working (better) now but it’s hard to tell exactly when it is or isn’t. Same with the language filter. Though random posts/threads (sidebar) doesn’t use filtering.
EDIT: Yeah, I think instance blocking only blocks users of that instance, as if a user of one instance posts on a blocked instance their post still shows up. Or close, I guess it’s the domain that matters as someone else pointed out.