For example: I tried to search all 3 communities from sopuli.xyz featured in this comment https://kbin.social/m/lemmy@lemmy.ml/t/2938/Which-subreddits-would-you-most-like-to-see-on-Lemmy/comment/6790/
search for y2kaesthetics did not work
for frutigeraero returned only my comment linked above
only for weirdcore succeeded
I have had the same (or similar?) issue.
I can search for example1@lemmy.ml and it works and I can subscribe in kbin.
But then I search for example2@lemmy.ml and get no results.