It occurs because the GPU maintains minimal power draw for standby functions even in a powered-down state. If the red light is blinking instead of solid, that could be a sign of a power delivery issue.
Maybe you have a problem with power delivery to your RX 6750 XT GPU. Do you have two separate power connectors from the PSU going to the GPU's power connectors (don't use a splitter from just one PSU cable)? Tell us about your PSU model and what else you have in your system that draws power.
As Albert Einstein said, "I could have done so much more with a Big Al's Computer!".
