Please help me figure out what is killing this grass

Portions of turf (we have Bermuda near Dallas, TX) on the fence line in my yard have randomly started dying very quickly - as in these patches just appeared in the last few days. This grass is getting plenty of water and sun, and the temps have dropped so drought shouldn’t be an issue.

I suspect grubs but not sure if there is something else I should be worried about. Thanks in advance for any replies!