The pull-down resistor was incorrectly calculated at 3480 Ω. It should be 5490 Ω.

The result will be that maximum RGB voltage (for a value of 0b1111) will be about 530mV instead of 700mV, giving a dim picture.

A fix was made in d869ca1, but the bug affects https://github.com/Neotron-Compute/Neotron-Pico/releases/tag/v0.5.0 (which we ordered from JLCPCB).