Telegram has disabled PiP for YouTube
Speech It’s about the “picture in picture“(picture in picture) function, which allows you to display one window on top of another. In this case, a YouTube video over Telegram.
Previously, the corresponding icon was displayed in the video preview window. But now she is gone. This information was confirmed from the official Telegram account on Twitter.
YouTube requirements indicate the reason for the absence of the function. At the same time, they emphasize that for Vimeo and Twitch “picture in picture” still works.