Hard to tell without breaking the button.
I've only twice held a 6D in my hands and both times indoors, but my 5DmkII and 5DmkIV both have shutter buttons that feel more like plastic than metal, especially when the camera feels cold, the shutter button doesn't.
All I know that first thing after getting a Canon camera Kim Jung Un, Putin and a bunch of other dictators and drug lords order a custom made whole diamond shutter button. There is a belief the diamond button adds +1 fps, doubles resolution, enables 8k60fps, and improves photography in general.
Of course I have heard them all. There are no dumb questions, I have heard no dumb questions, therefore it is irrefutable logic I have heard all of the zero.
I actually think custom shutter buttons would be cool. Favorite sports team, where you went to school, "Keep Calm, drink beer." "Fire!" etc... Where is Graham when you need him?
thanks fir ur answer! i was just curious thats all. my 80d shutter button scratched real easily and usually glossy black plastic does that. was curious if a full frame camera, had a better quality button like them nikons! lol