I do the same, normally once they are rooting out decently, they normally work really well in my experience, i have heard good things about rockwool as well but havent tried myself.
Interesting, you know i could see that happening, i have had to deal with root aphids a couple times now which means ripping up my root ball after harvest looking for them and each time i could still find the jiffy pod in the center, i expected that the pod would get ripped apart but it stays as a really tight root mass which could definitely cause the plant to stunt due to constriction, like a small part of the plant is always rootbound, i have heard good things about rockwool
In my experience they dont degrade at all, the roots are simply strong enough to rip through them but even after 4 mths when i check my root mass i can always still find them intact with a compact root mass inside, i could see that causing all sorts of problems, what do you use instead?
I believe one of my plants was stunted but someone told me that I could peel the outer layer off the jiffy pod before planting into pot I’ll try that next time to see if it helps I could be wrong