Our stove is German (not Chinese) from Bosch, top model. We never set the temperature above 400. However, steel pans warp every time we put them in the oven. I am an engineer by training, I think I know the problem: the technology is not strictly followed (Made in China?), the molten steel is not uniform. Different density across the volume leads to different thermal expansion, which in turn leads to warping. photo attached.
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