I’m not surprised stuff like this might happen to the additional mugshots, the implementation uses RAM addresses the original game didn’t use, surely for a reason. Some emulators might allow it, some don’t.
Ultimately, my benchmark is original hardware (my modded PS2), and on PC, Mednafen PSX/Beetle PSX, which was the most accurate, at least back in 2019 when I worked in X6 (I’m not so sure now, it might be Duckstation). And last time I tried it, it worked fine in those.
For what is worth, I’m gonna test if this issue happens in v2.5 using PCSX too, just to verify if they were introduced now or if it’s always been there. It’s possible there might’ve some regressions, but honestly I would be surprised (I didn’t touch anything related to mugshots)
edit: tried v2.6 on PCSX Rearmed on RetroArch (latest version of the core, I just downloaded it). I didn't get the issue either. Could you try updating the core and see if it still happens?