DTG Print Fading After ONE Wash

Hey guys. I'm a blanks manufacturer and ran a project for a client making 100% cotton tees.

He got the tees printed and the print ended up fading after 1 wash. The tee is 100% cotton, pfd (not dyed), has been enzyme washed (pre-shrunk). The customer is claiming the printer used authentic ink and hasn't changed anything on his settings. Any idea why this may be happening? Any advice would help.