I can confirm that page reloading is somehow related to the tab groups sync. Just today I was watching Netflix on my iMac in Orion saved tab group. Put the computer to sleep and switched to MacBook. Then opened that same tab group and tried to resume from there - which resulted in page reloading every couple seconds.
Then I opened Netflix in a new window (instead of saved tab group), and it worked without any issues.
So my guess is that it was trying to sync the saved tab group over and over again and refreshed the page.