I don't think signing onto an agency would be a step any influencer acting as a semi-escort would take. All plausible deniability is out the window at that point. I'm sure they don't even think of themselves as escorts, and if everyone their circle is doing it too, it probably seems normal to them.
I think they view it the same as taking coke recreationally vs being an addict. They wouldn't describe themselves as addicts even if they're sniffing everyday and half the reason they sell themselves is to fund the habit as much as support themselves. I'm sure they deride the girls who've went all in and got an ad on an actual escorting site, ignoring the reality that they're just one missed rent payment away from it themselves and a silver painted turd is still a turd.