See also this: https://www.reddit.com/r/Corsair/comments/kt81io/corsair_rm750x_fan_spinning_at_idle_half_of_the/
Link to Reddit sadly, but more people seem to have “this issue”. If you also have a GPU in there, you might just be taking too much from the PSU to idle.
Yeah, but if it measures every 1 gram at 0.98 gram, it will display less in the end