I don't think porcelain is a durable finish for a grate. My old cooktop grate's porcelain finish has come off nearest the burners and it's only a Jenn Air-not nearly so hot.

Porcelain does not bubble!! If your finish bubbles up then you don't have porcelain. Porcelain is fired at 2000-3000 deg F. The flame temp of a gas burner is probably up in this range. The burner grate does not reach that temp because heat is conducted away from the flame contact area by the rest of the grate and your cook pot. Porcelain like everything else comes in varying qualities and some might chip off or crumble or wear off. In order to form a bubble it would have to become a liquid or at least a semi liquid paste. Porcelain just won't do that.
I'm not sure what porcelain would do if it was heated over 3000 deg. You can't get to those kind of temps with an open gas burner.

Porcelain coating is expensive and Kitchen aid may be using a cheaper coating. There are some high temp powder coatings that are supposed to be pretty good. But aparently not for direct flame contact.

I’m having the same issue with my grates. They started to peel almost immediately.

kitchenaid told me this is “cosmetic “.and covered for 30 days. My $2200. range purchased 6mos ago looks awful. Shame on you kitchenaid.

Thanks for posting. I was just about to submit a claim for the grates as they started to peel immediately. I'll see if they will deal with my 3 month old range otherwise I may have to address it via social media.

I'm so glad I found this. I thought I'm the same things. The grates are horrible quality as mine on the larger burners have had this issue.