I think it's because you used the unofficial app and you are now on the Whatsapp blacklist with your phone number.
This will never be due to a Xiaomi.eu ROM.
My 13 Pro works fine, test follow steps: (with losing all data, make Backup first!)
- Flash Stock ROM, with format data (Xiaomi Tool)
- Follow steps on first Post (with TWRP a14skk or fastboot mode)
Yes, i updated first TWRP and after that, i install HyperOS. I have a PIN in TWRP which i have not lost with update. I update TWRP a14 directly in TWRP a13.
I tried with new us account but my wait time is now 1368 hours anyone idea? I tried with my original account from switzerland and after 600hours wait time it reset to 531 hours .