I believe yes (for a few years now) , based on its appearance in almost every mainstream language (js has a whole FP paradigm some swear on, java, c#, etc).

I think it is hard to find an exact reason, big languages introducing them both cause people to become familiar with FP and more people knowing FP will make languages better implement its features. It simply just got ready for prime time after several decades of lingering in academics - probably the hype of reactive frameworks added to it a bit as it made many people experience the pain-ease of managing frontend state before and after the paradigm shift.

I'd say it's spiking since 2020 at least, 2018 was the first year I experienced it.

It might have multiple reasons. ES6 and react should probably bear the lion share of the blame (personal opinion, in now way a fact) .