I sync contacts one way from outlook 365 pst on windows 10 to google contacts. Birthdays are no longer being uploaded to google (anniversaries are). I also created a test pst with dummy names which also don't sync. I tried the same test on a friend's laptop also with outlook 365, it doesn't sync birthdays either.
I noticed the same.
Waits for fix from Google API, see https://issuetracker.google.com/issues/200184636
seems to be fixed according the issuetracker comments, please doublecheck with latest version 4.1.22