Hi @xonemo welcome to the /e/ forum. In your position the first thing you want to know is the device codename. As a first step please use this [HOWTO] Find device codename.
Meanwhile I did an internet search for Custom ROM + Redmi Note 8 2021. This suggests to me that the 2021 Note 8 is indeed different from previous versions.
My first guess is that your device is the “biloba”. Perhaps you could confirm this?