I tried out RouterOS v7.12.1 (stable)
In WireGuard > Peers at the bottom of the page is an Output of a "new" QR-Code-Generator.

All my Peers have the same Content and doesn't match my configuration:

Did you notice that we have ROS 7.14 available? Did you check it?

had the same issue on winbox
switching over to create peers via CLI (SSH or terminal window in winbox) solved this for me

Reconfigured my Peers, added some aditional Data and the QR-Code-Generator works fine now.
Problem solved!

@SMS

Can you explain what additional information needs to be filled out?

The QR code is still not displayed in Winbox.

Is that (QR code) available? Cannot find it on 7.16.1

Thank you.

Reconfigured my Peers, added some aditional Data and the QR-Code-Generator works fine now.
Problem solved!

Can you tell us in details with screenshots what you did to make it work?

Client section:

Fill in the fields:

client address
client dns (optional)
client endpoint
client keepalive (optional)
client listen port

These fields generate QR-code.