Last I tried it, iCloud for Windows didn't integrate with Firefox, though.
I guess Apple does not think that 2024 will be the Year of the Linux Desktop.
If password managers could interfere with password fields in Firefox without its help, malware could do that, too.
Or is there a generic password manager API on Windows that Apple doesn’t implement?
1: https://en.wikipedia.org/wiki/Usage_share_of_web_browsers