Nice! Unfortunately I couldn't upload screenshot because itch error, but to me the bug specifically happened in swamps with the white monsters with flower heads (both variants). So I think the criteria for this bug to happen are
1. Enemy only has H-attacks (grabs you instantly without dropping on the floor with attacks)
2. Enemy has hurt stun animation if you attack them.
So what happens is when you hit enemy and they grab you at the same time, Syahata disappears, enemy becomes permanently stunned as if the H-scene starter. You can see the struggle bar but can't do anything. Just stuck forever