So the problem was the topojson.
In that case, I guess, I would have continued with the dataframe. I mean in order to manipulate it and then send it to VegaLite.
Thank you for your time. I will check the code where you are manipulating the “json” file.
I would say, that the problem is, that it is difficult to find the proper syntax for the vegalite specification. I only took the easier approach to come to a solution. I don’t think it would have been easier with the dataframe.