Invalid Mi 9 - Widevine is L3, even when returning to Stock ROM

[StardustCat]

Hello, everyone!

This has been plaguing me for months, though only now I decided to ask for help.
I really don't remember flashing the persist from someone else, so I guess it's from my own device. I know for sure that the IMEIs are the same. Does this prove my persist validity?
Even if I flash the stock ROM (Global EEA) and lock the bootloader, it still shows Widevine L3
Is this normal for the Mi 9? Other people have the same issue on this same device.

EDIT: typo
EDIT2: Changed my post to "Invalid". It seems you lose even after flashing your own persist, so there's nothing that can be made about this :/

 

[Poney70]

Hello,
Writing/flashing "persist" partition (only once) on Xiaomi devices = losing Widevine L1 certification for ever (even if you flash from a backup)

 

[StardustCat]

Wait, even if it's my own persist?

 

[Poney70]

Wait, even if it's my own persist?

Yes...

 

[StardustCat]

Oh, I see. That's too bad. But now I can stop my obsession with trying to solve this, haha.
Thank you ^^

 

[Alan098765]

What if you flash fastboot rom,could that not restore

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