Personally, I have never seen this many issues with Windows like today. Even way back in the Windows Vista days. Woah, Windows Vista will be 20 years old in November...
If you are forced to still be on Windows 11.
This file can be found in the following directory,
C:\ProgramData\Microsoft\Windows\CapabilityAccessManager\
Then see if it shows a huge file size.
Windows Latest found that one particular file called “CapabilityAccessManager.db-wal” can use most of your system storage.
If your PC is affected, the safest fix is to install Windows 11 KB5095093 from Windows Update, or wait for the July 2026 Patch Tuesday update, where the fix is expected to roll out automatically.
Outlook classic is one of the better examples of a legacy app with tons of integration capabilities that should have been overhauled years ago. The way plugins work is probably related to your issues.
The modern Outlook app is significantly more reliable but has its own quirks that are pretty painful when coming from classic.