Well it’s kind of normal. The colorspace is different between PC mode and Consumer electronic devices.
RGB is computer mode. In that mode, the video card sends the image like if it’s connected to a computer monitor. When switching to YCbCr, the video card sends the image like if it’s connected to a TV, in the same way as a blu-ray player would do.
When selecting 720P, we assume you want YCbCr pixel format.
