AFAIK, it's not recommended to play with Persist partition (incl. even restoring your own Persist backup) because you can loose some info specific to your device. I didn't play with but I've seen discussions about a year or two ago (unhappy users who complained about and about Xiaomi for that)Legit question.
Back in 2018 i had a mi mix 3 5g (terrible phone, no updates) and around that time i tried pixel experience rom and end up with my persist partition broken, i'd get security popups saying they couldn't use xiaomi track service and stuff like that. At the time i was told it happened because i installed TWRP, and it tampered with the persist partiton.
That being said, i have a chinese MI 11 to arrive this week and want to install xiaomi.eu rom. Will i damage the persist partition by doing so? Is there any way to backup it before installing TWRP?
Thanks.
Anyway, with root, you can backup Persist through adb:
adb shell
su
dd if=/dev/block/bootdevice/by-name/persist of=/sdcard/persist.img
persist.img will be saved to Internal memory
To restore, replace the source (if=) with the target (of=) and vice versa
You can do the same through Terminal app, however without:
adb shell
Some versions of custom recoveries like special builds of TWRP, SHRP, BPRP, Orange Fox can opt you to flash persist.img to Persist, or they can even allow to choose Persist partition when taking Backup and Restore