If that’s the case, now you have to do what us wayland users have had to suffer through this whole time and set an environment variable to tell it to run in X11 mode :)
If an application only ships with Wayland, then… well, I guess you’re using Wayland now.
Wayland is X12 - this is a “get onboard or get left behind” proposition. Nobody’s forcing you to switch to Wayland, but life is going to really start sucking for you soon.
As with all Open Source, it requires someone who wants to continue to support it to do so. If nobody wants to support X11 anymore, then it’s either your responsibility to pick up where they left off and code the X11 stuff yourself (and ideally give back to the community that’s been giving to you this whole time), or pay someone else a lot of money to do it. You don’t get to complain about something being given to you for free suddenly not being maintained otherwise.