Today Pavel Durov just announced the launch of their dedicated platform to sell/buy premium Telegram usernames. Checking that list, I've searched my channel's username and it says is coming soon: https://fragment.com/?query=%40kissfm
Going back to my channel to make sure this username belongs to me (my channel), I've noticed that the channel was transformed into a private channel, without username!
So telegram just literally stole my channel's username to sell it!
Durov, what you were saying about privacy and security in Telegram? You just dropped its level yourself!
P.S. check if your usernames still yours!
And I was mad at first but it was equally my fault for leaving my public group inactive for more than 10 months, which is probably why the username disappeared.
It's a real problem on other social media websites too. For example, a totally inactive account on GitHub claimed an org name and it has no repositories, no information, It's totally empty and I can do nothing about it. Not even report it so that GitHub can look into it and unfreeze the username.
EDIT: I just checked the dates and the channel was inactive from November 10, 2021 to August 26, 2022. So basically 9-10 months. Previously, I wrote 3 months but time flies I guess.