What is this?

I have this. What is it. Why is it. I have not touched the animation. I have no actions, nothing in my NLA, no keyframes, no animated values on any of my bones. That frame’s number shows up green in the playback.

I can’t get help on my own because the words “green line” pull explanations of what the fucking scrubber is of all things that need an explanation. This is the kind of crap that makes people not want to use Blender.

https://docs.blender.org/manual/de/dev/editors/timeline.html

I read it like three times. I don’t see it.

Edit: FFS found the right stack question. It’s the frucking Grease Pencil. What a bloody stupid hangup. I mean, you understand, I’m not about to start building a complex animation with some BS I don’t know what is in the middle of it. I love Blender, but sometimes man. Make that line black or label it or something.