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11 months agoIt looks like a manufacturer’s defect to me. Looks like injection molding gone slightly wrong - maybe a bubble or a mold not quite filled up. I worked in a place that made plant pots and sometimes they came out of the machine with gaps in the rims, and I had to stack the good ones and toss the bad ones into a bin for the grinder. Looks like they skipped that bit.
If they’re injection molded, and there’s a problem with the flow or the pressure, it could produce several runs that have the same void in one pan before someone notices and fixes it.