Hi Marilyn, my son welded a a pot onto my glass cooktop years ago...
He was boiling water to make the bubbles for a bubble drink, and left the stove on for about an hour.
Needless to say, the pot boiled dry, and melted onto the glass cooktop, and left a matte, black stain about 3" in diameter. I scrubbed and scrubbed with the cooktop cleaner, and I scraped and scraped with the razor blade thingie.
The mark remained, but it seemed okay to cook on it, so I've used it. At first, I worried that the black stuff would melt onto my other pots, but it didn't.
Over the years, the spot got smaller and smaller, and now you just see a little bit of the outline left.
I would hope that your stain would be less permanent, since yours is burned-on-food. Mine was burned-on-pot.
Good luck!
I tried to take a picture of it...
https://recipeswap.org/fun/wp-content/uploads/Finer_Kitchens/100_1452.jpg