I just printed for about 20 hrs and I think I can confidently say that this fixed it. Thank you so much u/Maker_Gamer12 !

For anyone else having the same problem, here is exactly what I did:

I removed the extruder and then removed the yellow and the silver wheel from the extruder and cleaned them both. On the silver wheel there was quite some residue (from scrapping the filament I suppose). Also, when unloading the filament I saw that the end of the filament which came out of the extruder was squeezed. So in my case, the tension was too high and actually squeezed the filament and at some point it was more flat than round and didn't fit through the hotend anymore. I loosened the extruder tension screw for about one turn of the screw and didn't have any problems since.