https://ru.wikipedia.org/wiki/Special:CentralAuth/πͺππͺπΆπͺπ·π½

https://ru.wikipedia.org/wiki/Special:CentralAuth/%F0%9D%93%AA%F0%9D%93%AD%F0%9D%93%AA%F0%9D%93%B6%F0%9D%93%AA%F0%9D%93%B7%F0%9D%93%BD

The participant wanted to register as "adamat" but the desired username already existed and he replaced the letters with mathematical symbols.

The registration verification extension compares similar letters of alphabets https://www.mediawiki.org/wiki/Extension:AntiSpoof/Equivalence_sets

Presumably, the set should be expanded with mathematical Unicode characters that look like letters https://en.wikipedia.org/wiki/Mathematical_Alphanumeric_Symbols