Sending in the whole system seems like an intentional deterrent to getting service. That's like sending in your entire laptop because it shipped with a faulty charger.
Mine had this issue. Luckily Gamestop had some in stock and they exchanged the whole unit. I think the way Nintendo is asking for the complete return is far from the respect they should give their customers. They should ship a replacement dock and let us return the faulty one once we have the new in hand. Like any company that cares about the user experience would.
The Nintendo Switch 2 dock offers many advantages, including a Gigabit Ethernet port. Sadly, some consoles only work reliably with WiFi networks. Nintendo support hasn't explained the issue and requests that customers send in the complete system for service.