This is bit shocking, don't you know wen the telegram group has been sold out and the new owner trying to edit the name to his preferable group name the subscribers may likely exit from the group?
That is why sometimes selling out telegram channel or group is very risky to the buyer
It's not actually shocking. A lot of channels were possibly been sold to new projects that want a shortcut building their community. They are making it look that many have joined their community but it's just a bought channel with members already.
This is the bad side of Telegram. They can change the name of the group and pass it to another owner. But what makes sense still is the true nature of the project of that group, bought or not if it's a bad project, it will remain a bad project.