if you use the latest xiaomi.eu/LRteam twrp then replace update-binary in the zip file for the rom, after that it installs normally.
Today I went from the last xiaomi.eu build to the 20.7.2 build by starting twrp, decoding the encryption and installing the rom. I didn't factory wipe, wipe data or anything other than the dalvlik/cache.
It booted and worked fine.
There is no TWRP that will deal with A11 encryption yet, so you can't update using twrp from one build to another.
To get back from A11 fastboot an A10 rom.