Diagnosis
This is almost always an HDMI handshake issue, often triggered by the projector's DynamicBlack feature or a marginal HDMI cable.
How to Fix It
First, disable DynamicBlack in the projector's picture settings. If that doesn't stop it, replace your HDMI cable with a certified Premium High Speed or Ultra High Speed cable, kept under 10 feet if possible.
If That Didn't Work
Try forcing the projector's HDMI input to a specific version: go to Settings -> System -> HDMI Settings and set it to HDMI 2.0 instead of Auto.
Heads Up
The PS5's VRR (Variable Refresh Rate) can also cause handshake problems; try disabling it on the console.