Ceramic Cooktop (non induction) getting damaged after use
It looks suspiciously like water that's been burned off at the edge of an overboiled pot.

On ceramic tops you get two kinds of stain. You get grease/food burned on, and that'll turn black like the inside of your toaster over, and you get the white mineral stains which comes from water drying around the edges.

The center usually stays clean because it gets super hot and will burn most anything away, but the edges don't get as hot as easily.

The way I clean them and it's considered rather unorthodox is to turn the burner on while the stovetop is bare. Let the edges get hotter than they would if a pan were keeping them cool, and much of this will burn away. After you see no further progress, turn off the stove and let it cool a little, but still above booling point of water, then use the green face of a scotch brite sponge to scrub any residue left over.

You can also try lye, but I am not a big fan of lye cleaners.