I struggled for two months on this issue. Tried everything from Regedit, stopping Adobe, Creating off line user profiles on widnows etc. After trying lots of permutations (different display, different PC on same display, different graphics card etc), it ws evident one of the software was in conflict and overriding windows settings - suspects were Windows Updates, Adobe CC and Intel.
The issue in my case (DIY PC, Win11/64) came out to be the Intel Graphics Software. Once uninstalled, log out and back in. It reset to all normal scaling! I have informed Intel, perhaps they will do something about it.
Note: Windows may reinstall this driver. Check Windows Updates > Optional Updates. You may find the Intel Driver waiting there to install. If it solved the issue, I would check all optional updates before installing en masse.
Hope that helps.