this is my first time reading part 8, but i have a theory on “josuke’s” memory loss.
if 『Soft & Wet』has the ability to take anything from any surface (the sound from the bathroom wall, the water from the policewoman in the hospital) without having any physical effect on the user, and “josuke” was in the condo before (at least, according to the girl in the bathroom), what if “josuke” used his stand to take his own memory?
whether it was conscious or subconscious, he may have used it as self-defense from the trauma of being held captive. or, if at all possible, “josuke” was manipulated into using his own stand against himself in order to let the main villain off scot-free. there’s also the possibility of it being an accident, but i highly doubt “josuke” would be stupid enough to allow that to happen