Apple TV 4k 128 Super Slow WiFi Speeds

Tangled power cords right next to the Apple TV box could be a potential source of interference. Metal parts, like from a cabinet, statue, device, or container, could shield or distort the Wi-Fi signal partially, causing interference. Nearby high power devices like a microwave or fridge could cause interference. If the Wi-Fi access point is too close, then the radio signals may not be optional. Interference may change with height. An Apple TV box at e.g. 1 ft from the floor may experience different connectivity than an iPhone at say 4.5 ft up. Something in the room is causing it, either very powerful or very close.

If you have an HDMI monitor, then you can relatively easily try moving things around to test reception, without unmounting the TV. If not for an immediate solution, then at least for confirmation.

it's doing the exact same thing my 2-year old one does.

It seems like the issue is/was not the device(s), but the environment.

Resolve Wi-Fi and Bluetooth issues caused by wireless interference - Apple Support

If you have an Apple Store somewhat nearby, then try making an appointment there, so they can evaluate the unit.

Genius Bar reservation and Apple Support options - Apple

(The second half of the page is about hardware support.)

Or talk to the Apple Support staff remotely.

Not sure what else to suggest.