Thanks for visiting Apple Support Communities!
I understand that you are seeing a green bar on your display during certain times of the day. It looks like no one has responded to your question. Here are a couple things that might help others answer your question:
Is the green bar only showing on the Eiffel Tower screen, or when using certain apps as well?
Have you attempted any type of reset from the watch itself, or the watch app on the paired iPhone?
Best regards.