I have seen many people report this bug, but it is generally difficult to reproduce because it is a low probability event. This is the first time I have seen someone trigger it in this space. I suggest you install the Warp Unbound timer mod to show whether it has triggered the protection correctly.
I’m up to 7 games in a row with at least 1 failed Warp Unbound. Question: Why not just make a separate buff for Warp Unbound that lasts for the entire duration of Scrier’s Gaze rather than tying it to the lingering effect buff? The swap between the two buffs is clearly the issue: If you hit 100 peril before the lingering effect “turns on”, you die. This is seems kinda like a race condition that a separate Warp Unbound buff would entirely resolve.