Velocity

Velocity cancels knockback: hits, arrows and explosions push the cheater less or not at all. It's often set to a fraction rather than zero, which makes it far less obvious.

Wherever the winner is the one left standing, that's a decisive edge: sumo, bridges, edge fights in BedWars and SkyWars where honest players get knocked into the void. On anarchy Velocity soaks up the push from crystal explosions and lets the cheater stand still under a hail of hits.

• Stands rooted after a hit, or moves far less than opponents do from the same hits
• Doesn't fly back from a crystal or TNT exploding right next to them
• Takes hits at the edge and stays on, when they should have gone flying
• Rule out honest causes first: netherite armor and Blast Protection reduce knockback, cobwebs and a wall behind the player absorb it

The server decides where to push a player and sends them the velocity. The anticheat notes the moment the client confirms receiving that packet and, from that tick on, simulates movement with the knockback applied: whatever keys are held, the player must move in the expected direction by at least some minimum. If the packet was confirmed but the movement looks as if no push happened, that's Velocity, not ping.

Walls, ceilings, water, ladders and collisions with other players absorb knockback honestly, so each flag is only evidence, and punishment comes after repeats across different fights.