[Suggestion] Add backtrack check

[lokspel]

[Photon-GitHub]

What exactly do you mean by „backtrack“.
Is this a different name for blink (as in, buffering packets to simulate lag)?
If so, I will likely not implement this as a well-coded blink is indistinguishable from a lag spike which is really problematic with false positives. Pure blink cheaters are something you probably need good moderators for.

[lokspel]

BackTrack is a lag-based form of reach.
The idea is that you stop receiving entity position update packets or delay them, allowing the client to gain an advantage by keeping the entity within a 3-block range on the client side, even though on the server the entity may be much farther away.

I think something simple like:
onDamageEvent: if (player.getDistance(entity) > 3 && player.hasConnectionSpikeSince(500ms))
would work. The idea is that players with around 400ms ping would still fail the range check, but their ping is likely consistent rather than spiky. Otherwise, legitimate players would also get flagged. Since we just want to cancel the damage, that can be left as a user-configurable option.

Most ACA checks are already heuristic-based; all we want is to mitigate this kind of advantage through damage cancellation or any similar method you can imagine.

[Janmm14]

This heuristic is rather useless. Backtrack provides advantages in PvP already with way lower maximum lag spikes.

A better heuristic approach should instead be implemented inside the anticheat which is providing the transaction-based reach-check. That is more secure, easier, to implement allows to weight in more data, etc etc.