I just used a tool from the "Shape Tools" plugin but the results were nonsense. The CRS of the point layer and my project CRS were EPSG:4326 - WGS 84.
Here is an image of the result: The correct result should be an ellipse around the point.
I realized if I change both the project CRS and point layer CRS to EPSG:25832 - ETRS92/UTMzone 32N. The tools of the plugin work perfectly fine.
That's the correct ellipse.
Any explanaition why this is the case?