NoRecoil cheat disables weapon kick/recoil when shooting. It gives huge advantage to players who use spraying weapons like Thompson etc.
Anti-NoRecoil tries to detect cheaters with recoil removed. It does that server-side (which means cheaters can't bypass it) and then it applies recoil server-side for those players.
However, server-side recoil emulation adds significant server load and detection is still not perfect and can cause false-positives, meaning that some players will be falsely marked as cheaters and will have server-side recoil added on top of the one their game client already adds.
You can test anti-norecoil feature by using sv_recoilemulation cvar:
set sv_recoilemulation <0-1>