I have a laggy connection and I haven't seen most of what you are talking about.
Also, it's mostly to do with them in my face.
They shove their face into my shield and strafe around me to try to duck around my shield.
I put my shield ahead of their strafe and on my screen they empty it into my shield.
Yet My shield takes nothing and either myself or my charge dies.
It should have required to bust the shield first.
Also, I've had times where someone like a Bangalore could shove their face into my shield and clip their gun through it to ignore my shield, thus a second layer should be added to require frontal assault to bust the shield before we can take damage. An forward overshield of sorts. That and widen the shield so laggy people can still stay ahead of a solo person trying to knock them down while they revive.