To be fair to Twitch, you cannot reasonably infer short of noting which IP addresses are used for mobile providers and which IP addresses are used for fixed-lin

To be fair to Twitch, you cannot reasonably infer short of noting which IP addresses are used for mobile providers and which IP addresses are used for fixed-line, and of course differentiate between metered (most US for example) and unmetered fixed-line communication. It's a warning if you use tethering, not if you use their apps on mobile.