Maybe it is, but I know that lots of us used GitHub way before Actions launched. I think even if Actions wasn't free, GitHub would still have a massive advantage because it is the most well known place to host code, especially by less technical users (which is where I see a lot of finger pointing going with the increase in GitHub usage).

I would not be surprised if a serious amount of this usage is not user-intended and instead the LLM just inserts some sort of CI job off the bat and people roll with it.