Man, that’s a bummer. Looks like the protective layer delaminated from the honeycomb. I think all you can do is replace the whole roof panel.
For what it’s worth, I had Sunpower flexible panels on my roof, mounted with all-around VHB and they heated up to 160F in places, and also trapped water underneath which helped them conduct heat into the roof. When one of them finally died, it got even hotter than that, actually smoked/sizzled until it burned through.
I have no idea if this is a cause in your situation, just adding this as a data point. Hope you find a reasonably clean way to fix this.