Adobe Acrobat Reader crashes without error message for signed documents

Situation and error description

1. reader crashes without error message if you want to set a signature with certificate or if a PDF signed in this way is opened/signed.
2. signed PDFs can generally not be opened, neither by double-clicking nor by “Open file” via an open Reader. It does not matter whether the signature is from the internal CA or was created by an external party.
3. PDFs without a signature appear to work, but crash immediately when signed.
4. no error message is displayed.
5. no error is written in the Windows event log.
6. the problem has been occurring since about the last 3, 4 or 5 released versions.
7. 2025.001.20566 is currently installed.
8. the problem occurs mainly on 2016 RDS servers, of which there are several, but also occasionally locally on Windows 10/11 computers.

What has already been tried

9. uninstallation: folder cleanup and reg. cleanup + reinstallation = error remains.
10. repair installation without computer/server restart: the error is gone, but comes back after server restart/new user logon.
11. cleaned up the Adobe reg. values of the user during operation and with the RDS user logged on, also cleaned up GPOs for Adobe, all Adobe folders in the user profile %appdata% ... deleted.
After opening the reader, the first start including EULA query etc. appears as expected = the problem persists, signed PDFs or PDFs to be signed crash immediately.