SteamOS appears to be disabling IPv6 by default

So for context, I don’t own any SteamOS devices, but I have many friends that do.

One of my friends was unable to connect to my IPv6-only server from their Steam deck despite their network and provider having IPv6 support. The IPv6 setting was off and they swear they didn’t turn it off (they’re also a very technical person and definitely would not disable it intentionally)

I had 4 other friends check their SteamOS devices and all 4 had IPv6 disabled.

Someone correct me if I’m misreading the situation, but it seems Valve is really going out of their way to not support IPv6, and is going as far as to override a default setting to disable it out of the box.

EDIT: Just to clarify, these are all devices that have shipped from Valve (e.g., Steam Deck and Steam Box) with no custom OS