I found another topic that seemed to be the same as this, but it was closed 2 years ago. End of 2021 and sync is not working correctly. I see a bunch of duplicate links, so I delete them and they just come back.
Any chance that you have updated Brave Browser on your Windows OS machine, and tested the issues you stated back in December 2021?
Maybe open a New Window and enter:
brave://sync-internals
in order to see if you notice some clue(s).
Ref. for that:
“https://www.davidagood.com/brave-browser-sync-not-working/”