That’s the reason why Sync is temporarily disabled for desktop since v.1.3 and higher. Brave Sync temporarily disabled on Desktop and https://support.brave.com/hc/en-us/articles/360042159452-How-do-I-re-enable-Brave-Sync-
Sync v2 is in the works. And this will fix the issue and re-enable Sync. Brave Sync v2 soon available in Nightly, will disable Sync v1
Available in Nightly and after that will hit Beta then Stable.