Input Buffer is how many frames of client input the server currently has queued. Higher values may increase input lag, rubber-banding, and latency.
New settings give players more control over Rocket League input buffering. These settings can be found in the Settings menu on the Gameplay tab.
Legacy - The default option used in Rocket League.
STS (Sim Time Scaling) - This allows the game server to instruct your client to subtly speed up or slowdown to maintain a smooth input stream.
CSTS (Continuous Sim Time Scaling) - A more aggressive version of STS. It uses a continuous feedback loop to determine game speed.
Both STS and CSTS are newer strategies for latency mitigation. These may be more effective for players with connectivity issues (spotty Wi-Fi, etc.). If you experience connectivity issues during a match, you should try switching from Legacy to STS or CSTS. If you see no improvement, change back to Legacy.
Note: Steam players can track their Input Buffering metrics in real time by enabling Network Graphs. This is turned on in Settings menu on the Interface tab. You can find more information on Performance and Network Graphs here.