Well that's it isn't it. I don't feel it's against the spirit of the rule (which I'm almost certain must apply to 4th too, even if it isn't listed currently under that category) but I'd rather be safe than sorry. Like you said it's early days so rules / categories etc will almost certainly shift and change anyway but I'd rather get a definitive answer now than get struck with a nasty suprise later.

So, as I'm sure those of you who play on PC are aware the game offers no official way to remove the ugly vignette or sharpening filter. Thankfully it can be removed with relative ease with the use of 3DMigoto to edit the shaders. Removal of these offers no advantage and, as I'm sure we can all agree, there should just be options in the graphics menu for them...but there aren't.

Before submitting my 4th Survivor run I checked the rules for that mode and saw nothing that would prohibit this so I thought nothing of it. However when I checked the rules for the main game it explicitly states: "Mods (including, but not limited to: first person, and "Gon' Give it to Ya") are not allowed."

Now personally I wouldn't consider removing these filters a mod...but what I consider a mod isn't important. I had them removed during my 4th Survivor run (if this means that gets rejected, so be it, I'd rather be open and honest and get a definitive answer one way or another) and I'd like to know on way or another if it's permissable going forward.