SOLVED : so this morning, I started the computer and it worked. That's it!
I cannot draw with the grease pencil tool, it acts like an eraser, although the pencil mode is selected. I found this topic, Blender 2.8 Grease Pencil displays [Report ERROR: Nothing to erase or all layers locked] when trying to draw, but it did not solve my issue. I tried to change "windows ink" or "automatic" in Edit > Prefs > Input > Tablet API . When I try to draw with my mouse, it only creates like an "arch", as you can see on the picture. it does not follow the movement of my mouse, it only draws a portion of an arch.
I'm using blender 2.9. Thanks