As I said, disregarding the print, the shirts from the gigs might be a different type, but are probably still Gildan shirts - just a different variant (i.e. Gildan Heavy Cotton instead of Gildan Softstyle or whatever).
I have an event shirt from London 2017 from the gig, with a printed label instead of a tag, and yeah it might be thicker, but I'd bet it is still a Gildan shirt.
As I said, if you look at the printed label on shirts purchased at 2023 gigs, they say made in Bangladesh.
The merch truck ones are also made in Bangladesh when you look at the tag.
So yeah, Gildan Softstyle shirts from the merch trucks, might be a little thinner softer feeling (matching the softstyle label), but shirts from the gigs will still be Gildan...just not SoftStyle.