I've set up a number of collaboration workspaces to share content between our enterprise portal (10.7.1) and ArcGIS Online (AGO). I created new groups during the workspace setup to send/receive content and found those groups to have delete protection greyed out in both the portal and AGO group settings page (see below). The delete button for these groups remains active, making it very easy to delete the groups by mistake. I've confirmed with ESRI Tech Support that this is expected behavior and the workaround is to first create groups in each portal, set their delete protection, and then associate them with a workspace.
Please stop disabling delete protection on groups created during collaboration workspace setup. We've experienced sync problems across multiple workspaces when just a single workspace was broken when a group for that workspace was deleted. There are too few warnings when deleting one of these groups so a secondary request would be provision of an additional warning when a collaborating group is being deleted. Thanks!