Weird font and personalization issues after september update

The fact that administrators are unaffected changes the diagnosis. This is more likely a per-user profile, policy, or profile-container problem than damaged system fonts or the display driver. The black background, keyboard layout, taskbar preferences, and ClearType state all reverting after restart are separate user settings; losing all of them together suggests the user hive is not being saved or the user is receiving a temporary/mandatory profile.

On an affected machine, check Event Viewer > Applications and Services Logs > Microsoft > Windows > User Profile Service > Operational immediately after sign-in. Look for profile load/save errors and events indicating a temporary profile. Run gpresult /h "%PUBLIC%\gp.html" as the affected user and compare the applied user policies with an administrator and with a newly created standard test user.

If the new standard user keeps its settings, preserve the affected user's files and have IT repair or recreate that profile through the organization's supported profile process. If every standard user is affected, inspect user-targeted Group Policy, Intune configuration, FSLogix/profile-container permissions if used, and any sign-in script that restores a baseline. Uninstalling display updates or rebuilding the machine will not fix a policy that reapplies the same user state at every logon.