Unfortunately, I have to agree with you. Not going back to Xiaomi after the amazing Mi A1 from all points for view and the both amazing (hardware-wise) and awful (from the software perspective) Mi 10T Pro. Anyway, I think I will get some custom ROM for the Mi 10T Pro after I receive MIUI 14 and discover there's nothing actually worth it coming with the update.
The only possible improvement to MIUI of any version would be to remove it completely. It is a total, intrusive and slow pain in the arse. I would never buy a Xaomi again for this reason.
As revealed by the code of a recently released Alpha test build, MIUI 15 will include two useful features. The first one is a more powerful and flexible clipboard, and the second will give the users a capability reserved to third-party apps so far, namely the ability to pump up the volume by 200%.