Shape map: topo JSON not well read

Hello,

I'm using a Shape Map to show neighborhoods of a town. A got the TopoJSON by converting the opendata GeoJSON of this town with an online tool. It works well.

Now I want to add surrounding neighborhoods. To do that, I had to merge 2 GeoJSON. I make that with QGIS, then I export the GeoJSON and convert it to topoJSON the same way. But when I add the new topoJSON to the Shape Map, the result is ugly.

TopoJSON viewed with a topoJSON viewer:

The same topoJSON in PowerBI:

Can someone help me?

Daniel