In the DTG process, the garment is placed on a printer's tray which is called the platen, the print area is designated by the size of the platen and the product's printable area, we have 4 sizes of platens
S - 10x12" ( ie tote bags, S size adult tees, S, M, L size hoodies..)
M - 14x16" ( default platen, adult tees, sweatshirts...)
L - 16x20" (only t-shirt dress)
The default platen we use is Medium size, but since the print areas are different on different products, we have to change the size to fit the product's print area. i.e. XL, 2XL and 3XL hoodies fit on the Medium platen in some way, S, M, L hoodies have to be printed on the Small platen. As in tees, M to 2XL sizes fit perfectly on the Medium platen, because of the seams on the sleeves, we have to use Small platen size when printing S size tees.
The kid's sweatshirts and t-shirts are the trickiest ones, unlike any other DTG products, as you know they have the biggest changes between their sizes, which means we have to use 3 different platens to print one product. I added some photos of them below;
As can be seen in the image, even though there is a big difference in the sizes, only S platen can be used on the 5/6, 7/8, and 9/11 sizes.
Another factor that limits the print area is the creases at bottom of the garment, it prevents us from printing in that area.
Also, as in all brands and product types, suppliers normally give a little bit of a tolerance to their sizes, kids sweatshirts have them as well, since the platen product fit is too close, some 5/6 sizes doesn't fit on the S platen and XS has to be used or S platen is too small for some 9/11 sweatshirts, we can use an M platen. So our operators sometimes have to decide product by product. Unlike adult t-shirts, for example, M platen fits all the sizes between M-3XL.
These factors above make the kid's sweatshirts one of the trickiest items to print and prevent consistency. Unfortunately, all products have some discrepancy to some degree between the print and the mockup, yet kids' sweatshirts have one of the biggest of them.
So small-looking prints weren't printed smaller on purpose ( although on a couple of photos, it could be printed slightly bigger and the operators have been given the feedback) but it is misleading from the mockup.