ValueError: The signature of key file and backup file mismatch

[SoilnRock]

So I'm trying to decrypt an old WhatsApp-Backup of mine. I pulled the msgstore.db.crypt14 and the key (158 Byte) from my android phone years ago but decryption doesn't work.
It's 100 % from the same phone - does anyone have any idea what might be the problem?

Would/Could it help to try to retrieve the key from my running phone or would this be a different key? I have always been using the same phone number/WhatsApp account.

Thx for any help!