I think it has to do more with "appearance fees", which is the main problem in doing a season like this, instead of everyday people who would drop everything for the chance. 3 alumni (Janelle Pierzina, Xavier Prather, Danielle Reyes) outright said on X that they turned it down because the show didn't pay them enough.
x13 and that's really going to eat into their budget.
Likely the same reason why TAR Australia's "Celebrity" Editions can only get D-listers and visit 4 countries a season.