%1$@|joined Telegram!
Legacy string. It was used for notifications. the text before | is a header, the text after | is shown on a new line
21
%1$@|joined Telegram!
21/21
Kind Tiger,
Dec 27, 2018 at 16:20
%1$@|joined Telegram!
20/21
Classy Beaver,
Jul 18, 2019 at 18:41