Not op, but I share the sentiment. In my experience, completely subjective of course, Xiaomi software on phones (I used 4 phones) is not polished, has a lot of bloatware/ads, and is not very stable. It's not all bad, since they have some good ux/ui ideas but it doesn't feel reliable to me.
Yeah, most Xiaomi users flash their phones with custom or AOSP ROM for a reason
Xiaomi SW isn't as bad as other Chinese manufacturers, but still...