bpm is to low during activity. maybe 20-30 bpm to low.
Done two workouts now and hade same issue (Strength workout). First time it "fixes" itself after 20-30min but I had to remove and re-attach the watch 4-5 times.
I now get down to 80 BPM in rest between sets (I rest 1 min) and before i never got down under 110-120bpm.
I could do more anecdote but something is wrong or the old firmware was wrong as it's a clear differance.