It sounds like they bought precut studs, thinking they were buying 2x4x8s.I keep thinking about this.
I wonder if they sold you someone else screw up?
I'd be ticked off.
Have bought lumber that's a bit longer than they should be, but never shorter.
Instead of 96" (+ a little bit, because they aren't cut to length, rather shrunk to near length) they got 92 5/8 whitewood or SYP studs (which are cut to length) to use as their joists. And if its like most lumber yards I've visited, the studs are usually next to the #2 grade 2x4x8s, I've seen plenty of people move wood from one pile to the other looking for straight wood, then leaving it in the wrong pile...
and I know you know this @aart, just explaining for others who may spend less time in lumber yards.
My local Lowes FINALLY moved all the whitewood to the back aisle and pulled (almost) all the PT to the front, stopped stocking studs next to full length lumber.
I hope they return them - whitewood studs are fine for inner walls of conditioned buildings, but they are a poor choice for joists outside, in a potentially sometimes moist environment.