I think one way you could improve is by making it clear that you sell two different brands of shirts. One is Next Level, and the other is a different brand that has a tag.
I previously ordered a size small and received the shirt without the tag, and that one fit me correctly. I recently ordered another shirt in a size small, but this time I received a Next Level brand shirt. That brand runs much smaller, so unfortunately the shirt does not fit me.
Because there is no way to know which brand will