If it makes you feel better, I’m having issues (not this specific one) with my pedals too.
My numbers are higher on my XC rally pedals AND my trainer by 20% but I can’t do the same ride over 2 sets of pedals and a smart trainer to prove it lol. I’ve sent them screenshots of my (garmin) HRM though and anecdotes to try and sort something out. I know they can’t just send new pedals out but I would be interested in returning these for a replacement pair. Otherwise I’m getting the Faveros.
I’ve tried different torque settings and different bikes and new batteries.
Garmin also say Pedals and smart trainers read differently. However they say smart trainers should read lower, the opposite issue to me.