Sounds like you are using it for personal use, so Dexpot, as suggested in the link you provided, sounds like a very good candidate.

The last update for mDesktop was in 2018, and the support department hasn't been around/active since 2014, it seems :-\, so I'd not even have tried it, would I've been in your shoes...

Close all active programs, also the ones in the system tray, one by one, and wait after you close one if the screen goes off. That should find you if one of your programs is causing this phenomenon.

Deleting the application-data is not very useful, you would have to log in to accounts anew, and set up configuration again, etc., and after doing that the (nearly) same amount of storage is used...

Best way to save storage space is to remove apps you don't need.