I’m posting in the Mac forum but i have this issue on Mac, iOS, ipadOS and the web app. I have a gmail account and a workspace account and multiple calendars within each account. My issue is that calendars randomly appear and reappear regularly, calendars get checked and unchecked randomly and the sync doesn’t work (or takes so long as to be useless). On the latter point if a meeting is deleted or added, it might now show up for an hour or two.
Basically the integration is broken for me.