Diagnosis
You're likely not in the correct picture mode or have post-processing effects enabled that add latency.
How to Fix It
Press the remote button that toggles picture modes. You must be in Game or User picture mode. In that mode's advanced settings, ensure BrilliantColor is set to 10 (it's fine for lag), but must turn OFF the following: Dynamic Black, Light Sense, Color Sense, and any noise reduction options.
If That Didn't Work
Check your source settings. On Xbox/PS5, ensure you're outputting at 1080p, not letting the console try to send a 4K signal that the projector then downscales (which adds lag). Also, use HDMI 2 port.
Heads Up
The 8.3ms claim is for 1080p/60Hz in Game mode with HDR off. Enabling HDR adds a few milliseconds of processing latency—this is normal.