It was a many months transition, and it's finally done
Fun thing, you can actually make a backup of all* your messages, groups, contacts, etc. So before leaving you can have all of your data in case you need that one contact or something
The final red flag was as that allegedly Russian authorities were messing with people's deleted messages. Not for the first time there are news that they could read, modify, delete, see location, and etc. Screw it, this is unsafe, I'm out.
Also, these days telegram is really at the state of a pile of garbage, bloated, buggy, and shady messenger.
Why did Telegram get so popular in the privacy scene compared to Signal in the first place? To my knowledge Signal came out first and never had a history of breaches or leaks.
Besides the ease of registration, the sync between devices make it easier. It can be frustrating not to be able to easily backup/restore/sync all your chats just like Whatsapp or Telegram. Yes, privacy/security, but i believe not everyone is chased by a state actor and you might want to have the option, as an opt-in maybe.