From what i have read i'm pretty sure that they (Kali Team) doesn't have the manpower to debug such issues.

Best hope is trying to reproduce this on Debian testing (on which Kali is based on) and if its reproducible (which is most likely the case) report it to Debian instead. If this is a bug in a Debian package (e.g. dm-crypt) it will also end up in Kali.

Thank you for your reply! However, I'm not very familiar with Debian's ISO. I downloaded the latest stable version of the ISO image from the official channel over the past few days and tested it, but I couldn't find the option to boot in persistent mode. Could you introduce which part of Debian's libraries or kernel Kali relies on when loading encrypted persistent files during boot? I will provide this feedback to them for review.

Short: I can't (as i don't know)

Long: As Debian is not a niche operating system i would assume there should be a lot guides available leading to an adequate setup. Important is that a Debian "testing" ISO (and not Debian "stable") is used