Well, I suppose that the cat is out of the bag, yeah? Someone has ported the input latency adjustment part of HDR to vanilla.
Since I co-authored this feature, I think it is fair that I explain how it works so that misinformation about it being "fair" or anything like that doesn't spread.
Honestly, we aren't quite sure why the SSBU development team did not synchronize this between players, it should have been one of the key things they did synchronize to ensure fair play.
The easiest way to explain this is:
- Player A: Has the mod and has set their latency to 2 frames.
- Player B: Does not have the mod, Smash Ultimate assigns them 5 frames by default.