No that's not true.
NMIXX is managed by a sub label called SQU4D which is the same thing with NIZIU, Boy Story, Day6, Xdinary Heroes
Those sub labels fund their own comebacks while Stray Kids, ITZY and Twice (Div1, 2, 3) are getting bigger budgets to finance since they are signed by the main label.
Do you have a source that shows SQU4D is a sub-label?
I've never seen it presented that way.
After all, I wouldn't call Studio J (Day6 and Xdinary Heroes) a sub-label either. Just another Division in JYPE.