I have started including an intro episode for anything I write now. I have a current light novel and the first chapter has some violence, but the story is actually more slice-of-life family/romance and fairly light. I found that a bunch of people were reading the first half-episode and leaving. I put info in the description, but I'm pretty sure no one really reads that, so now I give a "what to expect" as an introduction, including warnings and triggers. That way they can decide if they want to read it right away, instead of making assumptions based on the first 900-whatever words, or reading and then dropping because it wasn't what they expected. Also, since it's a new episode, your current subscribers still get notified - I know I had a bunch go in and read it even though they were already 18 episodes in.
I only did it a couple weeks ago, but my percentage of people leaving after the first half-episode has decreased. It's not like my writing got any better, and my genre didn't change, so I'm going to assume that helped at least a little.
Maybe sending out something to subscribers, or posting something in the latest episode, to tell them of the changes and that the actual comic will not have a change in content? I do agree with what others have said, though - it would be nice for comic artists especially to be able to distinguish between nudity and sexual content. But even "sexual content" is vague, so ultimately it still has to be up to the author...