Host system: Linux Mint 20.3
Guest system: Windows 10 v.21H2
CPU: AMD Ryzen 7 2700X
Problem:
Before installation of the VirtualBox Guest Additions I can scale 1600 x 1200.
After installation only the maximum resolution is 1024 x 768.
My two screens supports:
First screen 2560x1440~60Hz, 2nd screen: 1920x1200~60Hz
Extension Pack has the same version number as the VirtualBox .
How can I fix the problem to have a higher resolution?

Best regards
Michael