https://pl.smuglo.li/notice/5986711 is pretty vicious antisemitism. Apparently I have succeeded in following this person now though. I'll see if I end up seeing their posts.
Update: I'm seeing them fave my posts.
Update: I'm seeing them fave my posts.
In any case, you should contact the admins of your instance, but most probably they have blocked that instance, as it appears on blocklists for being a free speech zone.