I'm not sure which year they added the extra protection ie skid plate but, if you are super worried about it I would install a aftermarket skid plate for it. I am the only one that I have ever seen that would admit to putting a hole in a def tank, did it on my 11 truck!!! I found a plate made by Ore-Fab (no longer in business) for $139.00 put it on and did not worry about it again. My 19 truck seems to be much better protected than the 11 was. Just my $0.02 your experience may vary.
2011 GMC Sierra 2500 HD 2500 4X4 Duramax Traded 162,000 miles!!
2019 GMC Sierra 3500 HD CC 4X4 Duramax SRW LWB Stone Blue Metallic