Why does my Wonder Pot now bake unevenly?
Your flame may look even, but check the heat diffuser component of your wonderpot in your photo - you see the sootmark? That's a clear indication[PDF document from Association of Home Appliance Manufacturers] that the flame isn't burning cleanly... soot is made of carbon byproducts that should have been consumed by a clean burning flame, which consists of both fuel (cooking gas) and air. The burner's job is to combine both to make a clean flame. That much soot means it's not burning efficiently, which leads to uneven heat.

It can also lead to the production of carbon monoxide, which is not a good thing.

You will need to clean and calibrate the burner so it produces a clean, pure blue-white flame that burns clean on the bottom of your pots, or replace it if that doesn't help. This should only be done by someone knowledgeable in gas appliance repair.