Android 11 upgrade totally killed my Mi A3 smartphone. IT would not even boot and I had to get the phone professionally repaired and the software reloaded!!! Why can't you Google ****ers test properly before you release an upgrade???
It has nothing to do with Google, and everything to do with Xiaomi or other 3rd party manufacturers. Google develops the code and tests it on Pixel phones, since those are made by Google themselves. They then release the code to everyone else, but it's up to those other manufacturers to tweak the code so that it works correctly with their hardware and software, and to test it accordingly (even Android One phones, since Google isn't responsible for manufacturing those phones). So contact Xiaomi and let them know about the problem.
In addition, there are times when an update just gets borked during the installation, which has more to do with an individual unit, rather than being a widespread issue. So it's possible you were just the unfortunate victim of a glitch (which again, isn't Google's fault).