Hi!
Just coping from the other similar thread: Kleopatra couldn't determine the GnuPG home directory - #3 by bernhard
In my case I have Gpg4win 4.4.x and GNU Privacy Guard 2.4.x.
Winget offered to upgrade GNUPG for 2.5.x then it broke Gpg4win.
I remove both and install older versions (2.4.8 + 4.4.1) and it works.