Since you are talking ArcMap there are two things you should try:
1. Delete your Normal.mxt file at C:\Users\<your user id>\AppData\Roaming\ESRI\Desktop10.7\ArcMap\Templates
replace 10.7 with your version. Since you downgraded delete the 10.8 folder you may find at the above location as well.
2. Have a different user login to your computer with a different user id and see if they have the same issue with your map.
If their account works and yours does not, that means your Windows 10 Profile is corrupt on the machine.