many people with pots experience that and also some which doesnt have pots (or so it seems) but have heart problems, other dysautonomia such as mvp.
anyway i also experience that.
i read some possibility of it is dysautonomia or the blood flow or the structural changes to/of the heart (i forgot the explanation but a doctor said it) etc unfortunately i didnt bookmark what ive read so cant copy it.
i and a few people also mention that its odd to them cause its on supine position which doesnt seem to fit pots which triggers by the upright position and blood pulling to the leg.
anyone find any theory refer to it?