Now it's clear why Telegram required bot developers who download videos from YouTube or TikTok to normalize links to a single format.

A bot developer had to report to @BotSupport that they had normalized links in their bot using the hashtag #storage_update, otherwise the bot would be limited in functionality.

This allowed Telegram to identify the bots that normalized links and now use videos downloaded by those third‑party bots for its own message previews: if a bot has downloaded a video, then when you send a link to that YouTube video you'll see a message preview with video taken from one of those bots.