How can I turn off the "username" case sensitive setting?

Hi Guys, first - happy new year 2021! :tada::beer::muscle:
One question: since when has login “username” been case sensitive? How can I change it?
Thanks in advance!

P.S.: Local I have MySQL and PostgreSql databases. Only PostgreSql has this problem, the database itself seems to be case sensitive. I’m just about to find the setting. :thinking: