An extension of type=file, which is the only way you can install a tinymce plugin, can not be updated with the joomla extension update and any updates are not detected.

However the joomla update component pre-upgrade check does correctly identify that an update is available

Steps to reproduce the issue

Install this simple extension https://github.com/brianteeman/slashtools/releases/tag/1.0.0
(you dont need to configure it)
Check for updates

Expected result

it finds the update to version 1.0.1

Actual result

Nothing found

Additional comments

Tested on joomla 4.3, 4.4, 5.0