Dutch oven for baking bread problems

Hi, I bought soon very cheap Dutch oven (around 31$, it was a promotion in Kaufland ) ,the brand is Spice & Soul, material cast-iron. The producer confirms it can be used in oven in 240 C , so I bought it with intention to bake bread. I read carefully the instructions in the manual - for example I brushed the walls and bottom with oil before putting it in my oven. I turned the oven on 230 C (at first use I wanted to try it with 230 C ,not with the maximum 240 C ) and put the Dutch oven in with the lid on for around 30 minutes. During the heating there were some unpleasant smell. After 30 minutes I opened the oven and took out the Dutch oven in order to put the bread in. When I removed the lid, the inner walls were with brown color(the walls were enameled but now the white enamel was brown), the inner part of the lid was also little-to-medium brown and the bottom was still white. And I noticed that the bottom has still some very small layer of oil on it. I suppose that where the brushed oil had evaporated/wasn't present , these places were brown at most and as on the bottom there was still very thin layer of oil, - that is why the bottom was with its original color(not brown).I put the bread in, it baked (30 minutes with lid on, then 15-20 with lid off), and then I took out the Dutch oven, took out the bread to cool outside and so on. The taste of the bread wasn't better than when I am baking bread directly in pots in my oven, the raise/height of the bread wasn't taller than when I am baking directly in my home oven but this is not essential for my question.

I want to ask - is it normal the walls of cast-iron Dutch oven to become brown, the inner part of the lid also to be brown after just the first baking? Also, there were some outside places where the Dutch oven had changed its original color(red) with some dirty dark color. I tried to wash the Dutch oven as is written in the manual - with hot water and casual washing-up liquid and after a lot rubbing(with non-abrasive washing brush) the brown color at some places became a little lighter, but most of it remained. Do you have such big change in color of your Dutch ovens after just the first baking? Also I proofed the bread with baking paper in order to transfer it easily in the Dutch oven, and the bread was baked with baking paper around it - I start to wonder does this baking paper blocks/disables the type of baking called 'radiation' (that is supposed to come from baking bread in Dutch ovens) and this to be a reason why the taste of the bread wasn't better at all than my casual baking directly in my oven?