Hi,
I believe I've found this bug and fixed this in the current /trunk, you should be able to check a new nightly build in a few hours. (Note that the nightly builds don't support the Windows 11 context menu yet, for this you'd have to wait for a new release).
Project Monitor added the red exclaimation mark whenever it had problems accessing the repository. Even on local networks, there may be the occasional glitch. However it didn't clear the last error message after the next successful connection, it only did it the next time it found a new commit in that repository. This probably explains the report of someone having 20 project with 11 showing an error, most likely the other 9 had a commit after the last error message.
For more details, check the tortoise-dev group or the source code.
Kind regards,
Daniel