How can I get Safari to work with b2clogin.com logins?

Quoting Stackoverflow:

It is a known behavior of many browsers to share credentials between subdomains usually because if you log in using one subdomain (login.example.com) and later go to another subdomain (say passwordreset.example.com), the browser provides facility for you to login easily.

Enter Microsoft and its b2clogin.com service. Companies that use that for authentication of their customers get subdomains there, like company1.b2clogin.com and company2.b2clogin.com. What does Safari do: it merges all these credentials together into a single credential for *.b2clogin.com. Result, every time you get the wrong credentials autofilled by Safari and the ones you need have been overwritten. You end up resetting your password every time you want to login and that reset then overwrites the credentials of all the others.

I'm now wondering if I need to stop using Safari, because this is unusable. I really do not want it but too often now I run into stuff that doesn't work and companies simply tell me to use Google Chrome instead. I do not want to use Google Chrome, I do not trust Google.

Is there a solution where I can keep using Safari?