Totally overrated chins from both men.
Do they both have solid chins, sure. They got some beards on 'em, that's cool. This idea and narrative that they have some sort of Roy Nelson, Mark Hunt, Robbie Lawler level chin is just silly to me though. Where exactly is the evidence of either man taking colossal punishment? They both took next to zero real damage before fighting each other. In 72 minutes of fighting I don't think Golovkin once landed a fully power shot on Canelo, not like he has on his past opponents which he has typically knocked out. Canelo landed one really hard shot on Golovkin in their first fight which Gennady just walked through, now that was super impressive.
All that said, you're acting like these guys wear the damage on their chins, both fighters don't really take much damage. It took fights with each other to really take any proper damage, and even then they were both extremely cautious and never truly put it all on the line.