Xiaomi phones are often bricked up Why

Rome and recovery Anti-rollback protection from Xiaomi - keep your eyes open!

One or the other is that ARP, the so-called "Anti-rollback protection"Perhaps you have already found one; here is a rather extensive post on xda on this important topic:

Excerpt translated with deepL.com:
Xiaomi's Anti-Rollback Protection Explained: How To Avoid Blocking Your Phone

Xiaomi introduced MIUI 10 Global Beta 8.7.5 for eight Xiaomi devices back in July. When users installed the update on their Xiaomi Redmi Note 5 Pro, they unknowingly saw a build with anti-rollback protection turned on. Users who didn't like MIUI 10 Global Beta found a nasty surprise when they tried to reinstall the latest MIUI 9 Global Stable ROM: their phones have been bricked! This wasn't the type of brick you could fix by restoring a TWRP backup, flashing a new ROM, or using MiFlash to restore a factory image. This is a tough, unrecoverable stone that will require using EDL mode to fix it. But EDL mode is only accessible if you have an authorized account. So many users have had no way of getting their phone repaired other than shipping it to an authorized service center or paying to use someone with EDL access to use the account. In this article we are going to tell you everything you need to know about Xiaomi's new anti-rollback protection so that you can avoid blocking your new phone.

Translated with www.DeepL.com/Translator

Here is the whole text:
Xiaomi's Anti-Rollback Explained: How to avoid bricking your phone

Take some time ... it could be your phone before Bricken preserve