Natty was on Sixteen when she was 12, so was Eunbyeol on Idol School. It being okay or not is debatable (especially when the shows maknaes almost never debuts, I say almost because Koki on LOUD was the big exception), but it’s not new
I mean I get that having trainees that young is not that new but it’s not like it’s just 1-2 of them. There’s like 10+ which increases the chances of one of them debuting lol I have never seen this many young trainees on a Korean idol survival show or the youngest being 11.