User Search can't find user with unicode top level domain

What happens:

Neither of these find the user:

• @payphone@zetsubou.xn--q9jyb4c
• @payphone@zetsubou.みんな
• payphone@zetsubou.xn--q9jyb4c
• payphone@zetsubou.みんな
• https://zetsubou.xn--q9jyb4c/payphone

This one @payphone@zetsubou.みんな even gives a weird bugged out result screen:

The follow button here does not work.

What is expected:

The profile of https://zetsubou.xn--q9jyb4c/payphone is imported and listed and can be followed.

How to reproduce:

1. The user does not exist on my instance yet and should be fetched.
2. Put any of the previously listed URIs into the user search.

Other Notes:

I don't know if it's an encoding error on the front-end or a pleroma-backend error. Edit: importing users with normal tlds works fine btw.