User explicitly shares location to all people nearby, discovers it is accessible to all people. Feature is disabled by default, and user must find this and enable it. They are not even prompted to enable it unless they seek it.
Most users will not conclude from "sharing how nearby" people are, that someone could pinpoint exactly where they live by triangulating.
Unless Telegram does some extra steps to prevent exact locations (see other threads here), they should name it "share my location" instead of "show nearby users".
People nearby.
Quickly add people nearby who are also viewing this section and discover local group chats.
Please allow on location access to enable this feature.
"Allow in settings" (a button)
Then you see a system location access dialog. iOS allows to choose between (always, when in use, nope) and optionally to turn off "high precision" setting (not sure how much, but it covers entire city when off).
Then you may tap another button named "Make myself visible". I didn't, but a list of nearby users/groups was populated regardless.
They also say you need root to software spoof your location, but I thought you could do this without root using Mock Locations in developer options. I'm not sure if that's just an oversight, but it makes me think they aren't exactly familiar with Android as a whole.
If you just want to spoof location, you only need to use the setting in developer options, but this is detectable by apps. For example, Ingress or Pokemon GO will refuse to work when it is enabled, so to actually spoof location on some apps, root is needed.
User explicitly shares location to all people nearby, discovers it is accessible to all people. Feature is disabled by default, and user must find this and enable it. They are not even prompted to enable it unless they seek it.