Ubuntu or Raspberry OS are not based on Debian testing which could explain differences.

As Kali probably not maintaining the drivers on their own probably better report an issue to either the driver maintainer or Debian.

Not sure who replied in the with the comment thread "Ubuntu and Raspberry OS aren't Debian Based" as both of these are Debian based, using the testing for Debian, Ubuntu adding their features after this has been completed, furthermore Ubuntu is based on a less stable version so with this in mind Kali should be more stable.

Kali are entirely responsible for the upkeep of the drivers for their Operating system. This was working as intended previously on earlier version and is the handling of the operating system of the driver itself.

As this erroring version is advertised on both your website and the raspberry pi imager I would ask the issue be revised again before reply.

Please re-read my comment:

Ubuntu or Raspberry OS are not based on Debian >>>testing<<<

Debian testing is way more recent then anything provided by Ubuntu or Raspberry OS and Kali just puling most packages from Debian testing and the responsibility to maintain and fix bugs within these packages lies at Debian and not Kali ;-)

Some one from Kali also mentions things like 0008849:0019925:

Thank you for your interest in Kali, but we are not able to deal with such hardware support problems. Please read https://www.kali.org/docs/community/submitting-issues-kali-bug-tracker/ first.

or 0008926:0019812 in the past:

We provide xfce packages (in this case xfwm4 I think) unmodified from Debian. So you should verify that you can reproduce those issues in Debian and then report them to Debian (or to the upstream project directly).
See https://www.kali.org/docs/community/submitting-issues-kali-bug-tracker/
We don't have the manpower to investigate those issues ourselves.

which most likely applies as well here.

Short: Report to Debian as the Kali team seems to not have capabilities to investigate such things on their own ;-)

So to be clear: The Kali team who produce the Kali kernel/Operating System that was working on this hardware previously, are saying that I need to go to Debian when two other Debian based OS's are working perfectly with the same setup? Which for absolute clarity: is deploying the Kali Kernel/OS to an SD card for use with a RaspberryPi4 which I'm sure your team have in order to perform testing and beta builds. AND again for absolute clarity: Kali is the only OS of all of the ones tested that is giving this behaviour. This isn't a hardware issue by the way, this is entirely software and all testing that I've performed points to an issue relating to Kali's handling of the network stack in relation to the ethernet port specifically. This is on multiple devices and is easily replicable.

I will also raise a ticket with the Debian Team however I please ask that your team that deal with the Kali deployment for arm also Check and test this also. Please If nothing else Humour me. This has been ongoing for a while.

This is also how i understand the Kali team statements i have quoted and that is the reason why i had asked them in 0008959 to make this more clear. Parts what i explained before seems to be documented by them at https://www.kali.org/docs/policy/kali-linux-relationship-with-debian/

Btw. this is not "my team", i'm not part of Kali ;-)