Feb 12 2021 02:23 AM
Microsoft’s Edge browser recently introduced sleeping tabs to conserve resources. Although this is a good idea, putting SharePoint Online tabs to sleep stops them reconnecting. I suspect it is because a refresh token times out and isn’t renewed. The solution is to add SharePoint Online sites to the list of sites that don’t sleep. Always-on document management is the best approach.
https://office365itpros.com/2021/02/12/edge-sleeping-tabs-affect-sharepoint/