Asked to change my summoner name

So I logged in today to my account and a screen appears asking me and offering me the option to set a new summoner name. I tried to set my current summoner name, but it said that no special characters are allowed. Anyone know what is this? My best guess is, I got reported for my summoner name and I had to change it. The funny part is that I chose a new summoner name, logged in, but I can change to my previous (still available) for 13900 BE. Edit1: I have no access to my email at the moment to verify if report was the case.
Best New

We're testing a new feature that gives the option to view discussion comments in chronological order. Some testers have pointed out situations in which they feel a linear view could be helpful, so we'd like see how you guys make use of it.

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