Ok, after the comment in the reddit thread, I’m able to reproduce consistently.
The issue is that, for some reason, if a login is used that contains case letters, it works fine on a desktop browser but not on mobile. So, the new player.twitch.tv is case sensitive on mobile browsers (iOS Safari) but not case sensitive on desktops (Windows Chrome).
So for example,
twitch.tv/ArmadaUGS/embed
redirects to
player.twitch.tv/?channel=ArmadaUGS
The latter url works fine on Windows/Chrome, but does not work on iOS/Safari. The old /embed url used to work fine, but now that it is redirecting to the player domain, it’s broken (on iOS). A simple suggestion patch that would fix existing clients and existing embed links out on the internet: When redirecting, use the lowercase version.
Therefore, twitch.tv/ArmadaUGS/embed would redirect to:
player.twitch.tv/?channel=armadaugs
This would be a global fix for any existing applications/embeds.