I ended up doing a clean install for a base image which fixed the issue. I don't have any affected systems to test on, but someone at Dell just sent me this in case anyone else is having this problem:Could you try deleting the below registry entry? This might resolve the issue. - Delete the regkey: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Appx\AppxAllUserStore\[UserSid] - Restart system
Hi, I've found this problem in recent batches of Optiplex 5090s and Latitude 3520s.  After upgrading to Win10 21H2 using the Media Creation Tool, creating a new local account and trying to run store apps or the MS store itself gives errors like "You'll need a new app to open this ms-calculator link".  A partial workaround is granting each account admin rights and running      or      will also work without admin rights, but the path is subject to change.  Wsreset, sfc /scannow, and other suggested fixes for similar problems have not helped. I was able to reproduce the problem by taking a brand new 3520 out of the box, making no changes other than upgrading to 21H2 and adding a local user account.  Windows-R>calc then fails with the same error. Is there something in recent Dell images that is causing this?  Is there a permanent fix, or should I just start doing clean installs on new PCs?  
Microsoft store breaks after upgrading to 21H2