Apple Watch showing AFIB only when laying on left side.

Hey everyone, I have a series 10 Apple Watch and its ECG readings are kind of freaking me out.

I have never had any abnormal ECG readings in doctors offices (took a 12-lead ECG a month ago) on my watch etc but yesterday I was feeling some palpitations due to having way too much caffeine so I used the ECG function on my watch.

When I was laying on my left side it said I have signs of AFIB, when I got up immediately after or switched to my right side it said sinus rhythm every time. I tried sitting up, standing up, sitting on my chair, being on my back, on my stomach and so on. I took like 50+ readings and it all came back the same - normal in other positions, some AFIB readings when laying on left side. I wear it daily when exercising and sleeping and during the 6weeks I have had my watch it has never detected AFIB before. I called my doctor as well and she said heart rhythm disorders don't magically disappear when I change the way I lay/sit and that everything is okay with my heart. When I am laying on my left side it will also sometimes say the recording is poor or it will show a consistent sinus rhythm 10 times in a row and then an AFIB reading once. Again - no AFIB readings in other positions ever, even when I take my ECG in another position seconds after an abnormal reading.

What could cause this? Also worth mentioning that I am 21 years old, have had anxiety for the past 10 years and drink caffeine daily.