ECG. Is this normal or a faulty watch?

Got a used AW8 a few weeks ago. I had heart bypass surgery several years ago and ongoing heart disease. Got the watch for the ECG and A-fib functions mostly. First I do understand having the watch properly adjusted and am under all circumstances always sitting with my arm resting still on a solid surface and touching the crown steadily. I’m not trying to record during activity. When I take a resting ECG everything looks good. Regular pulses on a mostly steady line. After I been active, walking or working, I cannot record a valid ECG. The more active I’ve been the worse the display becomes. Instead of recording the hearts beat on a steady line I just get a lot of random up and down spiking. I can duplicate the random spiking during a non active ECG by just slightly moving my finger on the crown. I’ve no idea if that is normal or if perhaps it’s a problem with the watch. I’m pretty sure and hope that’s not actually a true picture of my heart activity 😀. The attached pictures are a normal rested ECG. One after mild exertion and after more exertion. Because I bought the watch on eBay I did purchase supplemental repair/replacement insurance. Is this normal, do I need to make a claim or are my expectations unreasonable? Thank you for taking time to read this and hope someone can advise.