One new feature on the Blue Tint’s primeknit is the faint grey vertical marks on the second stripe (the one sitting under the text stripe). The problem with the fakes is that they either don’t have them or they are not visible enough.
I highlighted this in the comparison above but I also made this zoomed-in photo. Note that the fake example has no grey lines at all.
Here’s an example of fakes that have the lines that are not visible enough.