I was at WDW a couple weeks ago. I had to show the app at Pop where I was staying, and at MK. I was not asked to at Epcot, where I made multiple purchases showing my AP card and DL. So I was probably there during the transition period.
At Pop, the clerk said that the problem was that people could alter the hand written expiration dates, so they were moving to a format that could not be altered. I can understand that. I don’t understand why they quit printing the info on the pass cards by machine in the first place though.
I have a very old phone, that does not support the current version of
MDE (updating my phone later this year) and between that and the glitchy Disney wi-fi, it took me a good ten minutes at Pop to access the pass, and about five at MK. I wasn’t in a hurry, and the registers weren’t busy, but I can see where there could be issues during busy times, especially as more international guests return and use the wi-fi.