Quick update - I just checked another DMM with a factory cal date of 22/6/2023, and it has a marking of "FPC0500D27B1" on the FPC leading to the display assembly, i.e. it also has the better display fitted.
It's hard to tell how much better this display is as the meter is in an extremely bright room, but it doesn't seem to show the "doubling" seen on the older part.
I'm gonna have a poke around digikey etc looking for easier-to-source compatible displays (need to get a compatible touch controller as well as a bright IPS panel), will post again if I find anything promising.
Edit: swapped the panels and the old meter is happy driving the new panel (I assume the reverse is true, will test tomorrow). Also noticed that while digikey doesn't have the D27B-CT SKU, they do have the D27K-CT, which is a panel rated for a higher LED current (and proportionately higher brightness). If the LED drive is a simple current limited supply then this might be the easiest drop-in replacement, with the caveat that we don't know if D27B1-CTN3 (what's on the sticker in 0x2102's post) is the same as D27(B/K)-CT (what comes up on the web/digikey). 73 bucks though!
https://www.digikey.com/en/products/detail/az-displays/ATM0500D27K-CT/12168275