I don't see how you could possibly give your full attention to one job when working for multiple at the same time.
I also wouldn't want an employee accidentally committing proprietary code/logins, which could be a huge security issue.
a 'side gig' to me means working on it outside of working hours, not at the same time.
This is just dishonest.
I looked around and noticed 3x more commits to private repos daily from his GitHub than commits to our company.
After confronting him he said people from his past companies must have been using his GitHub account. (Are you kidding me)
I asked him to solve it then and there by screenshotting and showing me what the private commits are. The screenshot had commits to two other companies.
They could also work on things in their free time and to be honest, as long as they do their work you shouldn't need to care. You only buy 8h of their time usually.
Camera off: Oh shit, I don't want to be watched in larger zoom meetings
Sharing one tab at the time: Crazy. How dare them.
LinkedIn is none of your business. It's their private profile and they can do whatever the hell they want with that.
I am not saying they aren't overemployed but your behavior isn't exactly at its best either.