An issue I've had for years and years, across 2 different iMac computers / installations / profiles. Galaxy just keeps updating itself day after day, sometimes multiple times a day.

Is anybody else having similar issues?

Sounds like it might be a permissions issue. A clean install would be a good idea, but I don't know where the data folders are on a Mac.
Open a support ticket, if you haven't already. You'll have to tell the chatbot the issue is of type "other" twice. Another Mac user might help you out before support replies.