Diagnosis
This is an HDMI handshake issue. The projector and source are struggling to negotiate the HDR/4K signal format consistently.
How to Fix It
First, bypass any intermediate devices like switches or receivers. Plug your PS5 directly into the projector's HDMI 2 port (it's the one with higher bandwidth). On the PS5, set the 4K Video Transfer Rate to -1 (instead of Automatic) and disable 120Hz output if you don't need it.
If That Didn't Work
Get a certified Ultra High Speed HDMI cable. The included cable is often mediocre. Also, on the projector, go to Display -> HDMI EDID and set it to 2.0 to force a stable standard.
Heads Up
If you use an AVR, ensure it also fully supports HDMI 2.0/HDCP 2.2. Older receivers are a common bottleneck.