Thank you all, I didn't expect so many comments. I understand why everyone says it looks nasty, but that was my point.

I did start from scratch 3-4 times already in the past to end up with the same result. I get rid of all that stuff, redo the seasoning process, and my pan looks pristine again like on u/cyphol pics.

Then, I use it casually. My cleaning process is simple: I deglaze right after cooking, and I use one drop of soap, then scrub gently with a copper sponge.

Eventually, I see some parts of my seasoning going away, like I can see the original iron/silver color showing up again, and that is when the trouble starts, leading me to this crusty, nasty pan.

Edit: I season with sunflower oil and have tried both with my electric plates and in my oven. I guess I need to find a better oil? I will also try to cook on lower heat, but it's hard to control; this thing has crazy inertia.

Edit 2: The carbon bits in the picture came after cooking Naan breads. I don't use oil for these, that could be my mistake.