Additional Context I tested it in addition on Ubuntu 21.10 and got the exact same error. It works perfectly on Windows 10, so my hardware definitely supports it. I also see that it is a DBus error, thrown by txdbus. Since Bleak switched from it (see problem here) now to dbus-next, would it make sense to change here as well? Sorry, I meant if you could show your bug tracking.
Similar to the previous Jakeler. Also, just to verify, is your 60-dbus-next up to date? I changed this again to deny it. However, have both of them added their users to be part of the Bluetooth group? Otherwise I can't even introspect the org connection, bluez. I hope this explanation helps a little.
In fact, Dbus is quite confusing, but I can recommend launching some programs that work and seeing with dbus-monitor. Also, graphic footers are useful for checking bus names, interfaces, etc. What's going on? Is this about the dbus configuration? Make sure you have these standard configuration files or an appropriate custom configuration.