I made this model in Blender and Textured it in Substance Painter. While in Substance I didnt see any problems, but when exporting it to Blender and applying the maps i got weird artifacts and color problems. I used Blender 2.8, I have good specs (so no performace issue), and the newest version of substance painter. I have not changed any settings in blender - they are all on the standard setting & I rendered with eevee. In Substance Painter I chose the Unity Setting for Baking.
Without Normal Map:
With Normal Map:
Material in Blender:
Normal Map:
In Sketchfab it works, altough i get pretty visible seams there. Maybe someone also knows a solution to that: https://sketchfab.com/models/9a6ee7b916b34d358621eae53d6d89a4
Thank you for helping me!