Hello, I hardly had time to look after the drone these days.
But I found out that I didn't plug the connector into the GPS correctly and a pin was bent. I fixed that now as you can see in the pictures.
So one step closer to the goal, now I have the I2C Error 7. Do you know where it is triggered and how to fix it?

I2C errors are not going to mean much if the connection is not right or the compass module is defective.

Betaflight has very few settings for a compass and your original configuration dump seems to show the correct settings.

I will suggest you double check the wiring, run a few continuity tests using a multimeter and also test for shorts.

Bent pins shorting other pins can have a damaging effect and you probably want to check if the GPS/Compass module gets excessively hot when you power up the quad.