Hello miui12 beta 20.4.30 for Mi 9T Pro/K20 Pro has outdated miui11 v415 gpu drivers while china closed beta has v454 i believe its caused by modified vendor by xiaomi.eu hope it can be fixed soon!
I believe the gpu drivers the xiaomi.eu team is using are different than the rest and that is one of the reasons you can't use the 90hz mod with their rom
