[dylz]

Pretty much this, I've noticed quite an uptick of traffic since WFHdemic started from mobile networks presenting non-mobile user agents. If you're on a typical 5G hotspot and suddenly start mass uploading, congrats, you've either run up a bill horrendously within minutes or run out of data for the month.

In addition, there are many countries (like India for example) where wired internet is not the norm and instead 3G/4G/LTE sticks or hotspots are.

Not to mention data caps are a thing on wired internet anyway, like Comcast in US.

[slykar]

There seem to be an option in Windows that let you specify you are on a metered connection. Probably one could check if the "saveData" option is selected to disable p2p.

[dylz]

As cloudy as Windows is, it doesn't seem to automatically detect/set that flag (and then you have the problem where people don't want to turn on datasave mode - like how I don't want iOS to only download updates over WiFi because I don't have any, I just want it to download it all over LTE), and getting all your website users to "opt in" to setting it is kind of an exercise in frustration to not automatically be using their bandwidth