It’s not the brand of the device but a problem with the technology:
If your heart rate looks wrong it probably is. My heart rate walking to work today was measured as over 180. Yes it was uphill and I was walking fast, treating it as cross training. But I’m 59 years old and the idea that I could sustain a heart rate of over 180 for twenty minutes with no discomfort is just absurd. Normally the same walk at the same pace takes my heart rate to 120 or maybe 130. I suspect the 180 was my cadence not my heart rate: the article explains how the technology causes the two to be confused sometimes.