Thanks for the input. It appears the users with affected by this I've interacted with are standalone PC users and not business PC clients on a domain or at a workplace controlled by GP. All currently appear to my Windows 10 Home users.
@ MHCLV941
Thank you for sharing your experiences with your Quickbooks clients. It starting to look like not all users were affected by the lost of total loss of functionality of IE. Of the 3 Windows 10 Pro PCs I checked, none lost it. Of the 6 Windows 10 home PCs I checked, 3 lost it, 1 had not and 2 had not yet received the Windows 21H1 updates suspected of causing the issue. I ran the updates to the 2 PCs that needed it and they never lost the the use of IE. I looks like certain conditions must exist on the affected PCs or perhaps when the PCs received their updates affected them. I have seen some references to the timing of certain KBs being installed that may have something to do with it. Just thought I'd share what I learned in case you were interested.
Thanks again for sharing, it helped me to look deeper into the cause.
I have submitted a request for help through the email address listed above by Eric_VanAelstyn.
It would be great if it leads to a fix.
Take care and have a good week everyone,
Mike V.