I have been playing a cloud-supported game several days on GOG now, and it always has the yellow arrow pointing down saying cloud sync failed due to heavy load. After a recent client update, it works for a bit, then keep failing again. Is it just on my end, or does the launcher has issues currently?

Double-check that the LSASS.exe Windows service has Internet access.
https://www.gog.com/forum/general_beta_gog_galaxy_2.0/cloud_sync_failed_for_all_installed_games/post5

Nope, still doesn't work. Followed the steps there, the steps here https://support.gog.com/hc/en-us/articles/360003899358-GOG-GALAXY-doesn-t-track-my-game-time?product=gog, and also manually allow LSASS through firewall. Nothing.

It did work several times though. Usually not long after I turned on my PC and opened Galaxy for the first time. But on subsequent exits-and-reopens it doesn't work.

yes the sign in server isn't working... yes the issue is at Gogs end and yes they know about it

It's weird, sometimes they work but mostly don't. Usually only works for about an hour or so before broken again. I hope its not my internet protocol issues and it will be fixed soon...