New Apple TV 4K acting as router and giving out IPv6 (ULA) addresses

I run a strictly IPv4 network as my ISP does not support IPv6 and some devices in my network still not ready for it. On my router I have disabled it on kernel level, so there is no way IPv6 is able to get into my network, or so I thought. Since about a week ago I started noticing that my computer and iPhone started getting IPv6 unique local addresses (ULA), so nothing on the internet, but still. They were in the range of fd94:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx:xxxx. I immediately went to the router and double checked all the settings, IPv6 was seemingly still disabled and the IPv6 ULA-Prefix was also empty. I tried some different settings, but I still kept getting an IPv6 address on my devices.

It seemed to me that a device inside my network was giving out these addresses, but which one? I started by removing all cables one by one from the switch and noticed that I did not receive an IPv6 address when the cable to the TV (and related devices) was unplugged. Checking further I noticed that the new 2021 Apple TV 4K was the culprit. Unplugging it made my whole network clean of IPv6, replugging made them receive IPv6 ULAs again.

I tried resetting the Apple TV multiple times, but this did not solve the problem. I also set it up without logging into iCloud, not using any previously saved settings. After resetting the Apple TV, the IPv6 address range it was giving out only changed (from fd94:... to fd53:...).

To be completely sure that it is not my own router I tried two different routers, with IPv6 disabled, but to no avail. When the Apple TV was not plugged in I only received an IPv4 address, but when it was plugged in I also received an fd53:... address (see the following images).

Is this a known bug? And is there possibly a solution to this? Or is my new Apple TV faulty? Some devices in my network cannot handle IPv6 (ULA) addresses, so I can basically not have this device connected to it (unless completely isolated in a VLAN).

I am currently running the latest version of tvOS 14.6. Updating from 14.5 to 14.6 went fine. I also tried using "Reset and Update," to possibly clean install the software, but I received an error message saying "Apple TV can't download the latest update right now. Try again later." This might be tied this same bug, where the Apple TV possibly tries to check for an update on an IPv6 server, but has no possible connection to it.