For Signal desktop on Linux to not require that I validate my mobile device randomly to read my encrypted messages. If it used GPG then this wouldn't be a problem.
What does this dialog look like? I don’t recall having seen that in my Signal desktop on Linux or Mac.
It looks like a yellow notification that says you need to re-link your mobile device, and in order to do so you have to take a picture of a QR code from your mobile device.