Standard Drop Loop Breaking

[TrackerPro16]

So I have used the standard dropper loop tied directly in and on the mono leader for, well, a long time. I am 63 so I have tied a few... Lost some gear recently and took notice that it snapped at the dropper knot. I was practice tying knots where I had access to a certified scale and tied a bunch of droppers complete with wetting the line before pulling tight. I was pretty surprised to find that over half broke at the knot below the 14 lb line strength. Two broke at 3 and 4lbs!
I tied a bunch of surgeons knot droppers and they all broke above 14 lbs and NOT at the knot OR loop. Obviously something is amiss with the standard dropper and or the way I am tying it, but I won’t take a chance on it any more.
Any one else notice this inconsistency?

[Amx]

I noticed the other year that the line I was using broke easier than it did in the years before. Also some knots are very poor in strength, and some knots don't last very long at all.

[skycap]

check on the age of your line. mono will deteriorate due to sunlight