Meanwhile we added a link to the GnuPG command line documentation at https://gnupg.org/documentation/manuals/gnupg/ below "More documentation" even in Gpg4win.

No, I have no admin rights on that computer: I installed the portable version, too. I saw that the previous version had been uninstalled before installation.
On a different computer I tried to reproduce the situation where GPG4WIN had been installed the standard way. I did not see the effect there. However when upgrading I got a message that the c library could not be written; that was because some Kleopatra windows was still open. After manually closing that, a retry was successful. Other software installers close the application before trying an uninstall or update, however.

Parts of the changes made for T7183: Kleopatra: Reduce certificates offered in Sign/Enyrypt dialog have been reverted. The drop downs for selecting the signing key and the "encrypt to self" key now offer the primary user IDs of usable keys again (instead of all user IDs of usable keys) and there's no button to open a certificate selection dialog anymore.

I looked at it but we probably need to rework/update the entire libtool stuff which has a high regression risk. Thus I give this bug a low priority because it is not a functional bug.

Just to be clear: You originally installed it as a portable applications and then you also installed a new version in the standard way?

I started Process Monitor only after Kleopatra hang so that I cannot find out which process started gpg-connect-agent.

Can you figure out who started gpg-connect-agent? Note that it is also used by gpgconf to reload, kill, or launch daemons.

And mind that the wording "This certificate is revoked" is wrong in any case, only the user ID is revoked, not the public key.

I stumbled into this problems myself yesterday. Time for a new release.

Log files for above deadlock

I just had another hang.