In German there is a rule on how to sort Umlauts (ÄÖÜß) in names:these are treated as if they qould be replaces by:

ä = aeö = oeü = ueÄ = AeÖ = OeÜ = Ueß = ss

and then sorted alphabetically.

Elvanto currently sorts people with Umlauts first, like:

Dörr, KatharinaDammer, RobinDeser, SigridDust, Karin

But it should sort

Dammer, RobinDeser, SigridDörr, KatharinaDust, Karin