I’m having the same problem with Manjaro Gnome. I tried downloading it several times and installing it on a couple of different USB drives. Finally, I tried to verify it and was unable to. I used Kleopatra on Windows and got the message:
Verified ‘manjaro-gnome-21.2.2-220123-linux515.iso’ with ‘manjaro-gnome-21.2.2-220123-linux515.iso.sig’:
The data could not be verified.
Are there different servers to try to download it from?