Mobile and app/web have differing ways of showing the "favorite" and "follow" flags for channels, ripe to lead to confusion and user error.
web/app: channel's "favorited" status is prominent; new users realizing they aren't getting notified of things on the channel will see that it's favorited and not understand why they aren't getting notifications. To get notifications, they have to figure out to click the ellipsis, then then "follow." It's also unacceptable that they have to click the ellipsis to even tell whether they're following that channel. There should be a "follow" button like the mobile app does, and it should be next to the star for favorite. The mouseovers (at least) should explain that "favoriting" makes the channel show by default in the team, and "following" gives notifications of activity.
mobile: it is not clear what the follow icon does, and again the user may not understand there's something else to activate if they already "favorited" the channel. Also, both the favorite and follow icons should both be visible.
ALL PLACES: the "Follow" icon should be changed. It currently does NOT show the current status of following, but instead the action the button would do. RECOMMENDATION: make it a tiny cartoon bubble (like the Messages icon on iOS), with a cross through it if off, and no cross if not off. This is complimentary to the full or empty favorite (which shows the status and acts as a toggle). Again, in both places they should be side by side to minimize confusion and improve the new user's understanding the difference of favorite vs follow.
ALSO to avoid confusion in all places: if "favoriting" a channel, user should have option to "follow" immediately (ideally a "follow" icon shows up beside the star if star is selected). Ideally that "follow" icon will default to ON or OFF based on user preference of which should be the case when a channel is followed.