Afaik, you can't block the entire instance yet, although some frontends or apps gives you ability to do that

There is an open request talking about it:

https://github.com/LemmyNet/lemmy/issues/2397

You could technically remove those languages from your settings ? That would require people to properly indicate theirs but could cut on the clutter.

Is not possible as of yet. The only solution is to defederate.

For now the only option is to block every community that you don't want to be seen individually. It is on the to-do list of the Lemmy devs though. But don't expect it in the near future.

I use this usercript: https://greasyfork.org/en/scripts/469297-block-lemmy-instances

You need to edit line 17

Here adapted to work also with MLMYM (https://old.lemmy.world): https://pastebin.com/z0mShfDP

I had similar problem and want to block all communities from specific instance (lemmygrad to be precise). I used community search by instance name and block them one by one.
It would be great to be able to select all results and block with one close click.

Would love to know how to do this. My feed is full of German and Korean if I choose all. I'd love to be able to avoid seeing posts in other languages I don't speak or read.