I really doubt the number of people using uncensored chat bot is that high. The drop of usage probably has more to do with novelty and AI general limitation.

The AI models are not always that easy to use and they are being developed at neck breaking speed, so I cannot imagine the numbers of people dedicate themselves to use such AI would be that high.

There is a niche of using AI chatbot as RP tool for sure, but it has always been a separated thing from the start and it cannot cause such sudden drop.