Steps to reproduce:

Example with the Character Information add-on

1. Open a file of the add-on in an editor, e.g. %appdata%\nvda\addons\charInfo\globalPlugins\charinfo\__init__.py
2. Open Add-on manager and remove Character Information add-on
   The status of the add-on is "Enabled, Removed after restart"
3. Close add-on manager and restart NVDA as asked.
4. Open add-on manager
   The status of the add-on is "Enabled, Removed after restart". This is expected because the add-on could not be removed due to the file opened in the editor.
5. Close the file of the add-on opened in the editor.
6. Close the add-on manager and restart NVDA as asked.
7. Open add-on manager and check the add-on's status
8. Execute steps 5. to 7. as many times as you want.

Actual behavior:

At step 7., the status of the add-on is "Enabled, Removed after restart".
The only way I have found to remove this add-on is to remove manually its folder or to reinstall it before removing it again.

Expected behavior:

At step 7., the add-on should not appear anymore in the list since nothing prevents NVDA anymore to remove the add-on after step 6.

System configuration

NVDA installed/portable/running from source:

Installed

NVDA version:

2021.1rc2

Windows version:

Windows 10 1809 (64-bit) build 17763.1935

Name and version of other software in use when reproducing the issue:

N/A

Other information about your system:

N/A

Other questions

Does the issue still occur after restarting your computer?

Yes

Have you tried any other versions of NVDA? If so, please report their behaviors.

Yes, this error has always been present, surely in all versions of NVDA 2019.3 and beyond.

If add-ons are disabled, is your problem still occurring?

N/A

Does the issue still occur after you run the COM Registration Fixing Tool in NVDA's tools menu?

Yes