I wouldn't consider the lower prices a crash but rather a correction or readjustment. Comics and collectibles across the board had an unprecedented run-up during the pandemic, around 2021-2022, and since last year have been stabilizing and returning to 2019-2021 levels. You might be interested in this thread:
Furthermore, Fantastic Four in general saw some big leaps after Marvel got the film rights back in 2019. While movie-hype books invariably dip down after film's release, I'd attribute lower FF #4 prices to the current market correction more than Wakanda Forever.