During a holiday trip, you meet some people and have a good time with them. While talking about your work, you tell them about an idea for a film you are working on. It is set in the 80s and is about a man who has two families, one in West Berlin and one in East Berlin. After the fall of the wall, his (West) son and his (East) daughter meet by chance and fall in love.

Two years later you see that a streamer has an upcoming series with exactly this core story.

Has copyright been infringed or not? Please explain your decision.