Something to consider. Just about any firearm can be put in a box for decades and still function flawlessly when removed. Kevlar has an expiration date. Most consider about 5 years IIRC. Less if exposed to the elements.
Just an arbitrary number picked by the Justice Department.
Manufacturers don't fight it because it does wonders in keeping sales numbers high.
I don't know of any objective tests showing degradation over time.
I have an old vest somewhere.. Over 20 years old.
Maybe I should break it out and do some tests...
Another alternative is the style that uses ballistic plates.
They gonna. Ha e to can steel plates & spray-on b3dliner.