Hey, I'm back again.
As you made letters in the config files that change the way mobs see, I suggest adding a letter (perhaps b for "bright") that mobs makes mobs sensitive to the light, and therefore struggle to see players and entities in the light. This way prioritizing light source blocks as defensive mechanisms against the hordes of mobs and avoid light if they do not have a player in line of sight. This would likely be great for horror style modpacks as this feature does not exist in any other mod and seems to fit naturally with your project. Let me know what you think!

I'm playing 1.19.2

If I had a nickel for each horror pack related feature request I've had this week I would have two nickels, which is not a lot, but it's kind of weird that it happened twice in a row.
the "night vision" flag used to be "nocturnal", which inverts the light detection for that specific monster. In practice it ended up being pretty horrible as bright (e.g. daylight) would nearly blind the mob. Design philosophy wise, since bright light already prevents mob spawning, it's a little cheap to have them repel mobs as well, I think. In addition, wouldn't dark light for reduced detection add to the spookiness factor?
I will add it if there's sufficient justification though.

Perhaps being blind isn't worth it, maybe an AI to flee from the light would be better. That way they still chase you into the light, but flee from it if they aren't pursuing you. And I'm not sure it needs much justification in terms of horror mechanics- Amnesia: The Bunker utilizes the mechanic of protective light and dangerous darkness pretty well and I'm not sure people argue about that. Whether or not it fits in your stealth mod... that may be different. I certainly cannot deny that it would be interesting to have some mobs see you easier in the darkness and others in the light which would add a variety of new gameplay situations.