The reference height and posture are different
Rule 14 defines the drop height by the player’s knee when standing. The player need not stand upright while releasing the ball. The ball must be released straight down in the prescribed way rather than thrown into position.
Imagine a player bending forward to release the ball at the same height their knee would occupy when standing. Their torso is low, but the reference height has not changed. A camera concentrating on the bent back can make the drop look much lower than it is.
Watch the hand and first bounce
The useful frame includes the releasing hand, the ground and enough of the player to understand the height. The final lie cannot establish whether the release was correct. A ball ending in a convenient spot may still have been dropped properly; an inconvenient result does not prove a faulty drop.
This ordinary procedure has modifications for specified disability categories, so the visual example should not be treated as a universal posture test for every golfer. For the case described, compare the release point with standing knee height and follow the vertical fall. Separate that question from whether the ball ultimately stayed in the relief area, which is the next procedural test.
Questions answered
Must the player be standing straight?
No. Standing knee height is the reference, not a mandatory posture.
Does a good final lie prove the drop was correct?
No; the release procedure must be assessed separately.
Sources & further reading
Official references for the subjects discussed. Service terms and device software can change.