Telegram publishes users' locations online
This reminds me of a study done more than 5 years ago on this exact problem.https://www.wired.com/2016/05/grindr-promises-privacy-still-...Gay Dating Apps Promise Privacy, But Leak Your Exact LocationResearchers in Kyoto demonstrate for WIRED how they can precisely track the locations of people using Grindr, Hornet, and Jack'd despite features meant to hide them.The mentioned research paper is here: https://arxiv.org/pdf/1604.08235.pdf