Iwatch heart rate spikes and EKG Afib

apple watch recording heart rate jumps/spikes from 120bpm to 167, I don’t feel any difference and saw a few other people post similar, is this a bug? Is it sweat build up under the watch?

it panics me when I see it suddenly go from 120 after being steady to 160+ within a few seconds, I tried the EKG feature and got mixed results and my first Afib reading which is also scary. I’m hoping it a bug or sweat but is that possible? for the jump and Afib? I have noticed post workout recording (didn’t notice during workout) of jumps to around 145 as well but never this high

my next workout I’m a little worried about now