Every single one of them reached the same uniform level of sub growth within a ten-day time period, within a few percentage points of CCV, on a perfectly smooth incline curve that then levelled out into relative near-zero growth for everyone except Poma.
Since then, their channels (aside from Poma) have grown by a few percentage points. If you take their post-debut growth into account, then their ratio of CCV to subscriber counts are normal; a 1/10 ratio of CCV to subscriber count, which is average to my knowledge. That leaves a minimum of 50k dead subs on every single channel, all of which joined in the same ten day window, and then inexplicably just all decided to never watch them again.
To put it another way, Rara Rocora has 53.6k subs. Her average CCV is 90-100, and average VOD views around 2k. The latter two statistics simply do not fit for a sub count that high, but would be perfectly natural for a channel with only 2.6-3.6k subs, aka the organic growth she has gotten post-debut. That leaves 50k subs just... unaccounted for.
I'm open to another potential explanation, but I just don't see one from where I'm standing. If it was one channel I'd call myself a schizo. If it was two I'd be suspicious but noncommittal. But three? Arguably four, if you factor in Poma's personal success and boost from being the clear stand-out of her gen, but that does muddy the waters slightly. That's a pattern I just can't overlook.