Yes, unfortunately they’ve removed Guides – for now. From the release notes on Blender 4.3:
“Drawing Guides
The guides in Draw Mode have not been ported to 4.3. There were multiple standing issues that made it difficult to convert the code without introducing more bugs. It was decided that this will be replaced with a more capable system in a future release.”
You can keep track of changes that are coming up via this page: https://developer.blender.org/docs/release_notes/4.3/grease_pencil/
