Interesting developments here.....

My blood pressure has always been around 125-80 meaning a pulse pressure of 45. Resting heart rate = 48.

This year, I have more time for training so there is around 25% more training time, my weight is also around 5lbs lower. Power is a little higher, but not much. Aerobic capacity seems better, however I am just done with base, so the long intervals will be replaced by short intervals and speed training

Two things have changed:

Blood pressure 130-66 giving a pulse pressure of 64, which is a bit concerning, resting heart rate dropped to 42.

My faithful Garmin hard plastic strap started losing the signal after four years of faultless operation.(Tried the soft straps, lucky if I get three months) Once heart rate goes above 135, the monitor drops back to zero. Changed battery, same thing. Bought a new Garmin plastic strap, same thing. Purchased a second new Garmin plastic strap, exactly the same thing.

Naturally, the conclusion here is that Garmin has not changed, but I have??? Weird.

Any insight from those into sports science will be appreciated.