How to handle 2FA forcing scanning QR codes?

So far I’ve been avoiding these and using oathtool, but now I’m stuck on a site that changed they way they do 2FA and I have to scan a QR code. How is everyone handling this? I have no interest in using a proprietary app on another device I’m probably going to be getting rid of soon. What apps for Fedora/Debian can be used to scan QR from the camera and screenshot? The only one I found (Authy) is also proprietary and I haven’t figured out how to get it to run on Qubes.

Generally, there’s an option to get an alphanumeric code instead of the QR code. Sometimes it’s a very small, almost hidden link somewhere on the page. I don’t think I’ve encountered a standards-compliant TOTP service that doesn’t offer such a code in addition to the QR code.