I will say it was rodent of some sort, be it a squirrel or porcupine or likes
and my bet is, some how when you last checked the camera you left some sort of scent behind from what ever you ate or handled, or a BUG maybe squeezed into the flash area and they chewed it up trying to get to it, or what ever the scent was on the camera
NOT a bear % sure on this, a bear would crunch it up and leave large teeth marks(I have had 5-6 cam's eaten by bears, got a lot of cool pic's of the inside of there mouths too LOL
and its why I learned to NEVER touch food or bait before handling a camera'
or wear rubber gloves to handle them CLEAN rubber gloves too!
and I also use a lot of bear boxes, more so to deter thief than bears!
also keep in mind, when your installing battery's and SD cards
if you have food scents on hands doing that, you can make your camera BAIT for things, animals have incredible noses you know!

I have MANY bird feeders chewed on like your can from squirrels, and they have eaten holes in many of my plastic 55 gallon drums too, that SED to have food products in, washed a few dozen times too, and they still smell scent of what WAS In them YRS ago!