Changed device lock code after encryption, and now it says data is damaged. Is this a bug?

I encrypted my Moto G4 Play using an alphanumeric password as the lock screen code because i thought that would increase the encryption key strength. After this, i changed it to a numeric lock code for convenience. Everything worked well until i power it off. Now it says the password used is correct, but the data is damaged and i must factory reset it. As far as i know, android encryption is implemented using luks and cryptfs, so i might be able to download dthe partition and decrypt it. Unfortunately, I also deactivated ADB and unrooted the phone, so i just erased everything. Is this a bug, or i did break the keys when i changed my password protection?