I keep asking for a while that Shields should be changed to counter burst. Prevent any white HP damage until you fully deplete blue HP. So, eg, if you are on Symmetra and get headshot by Widow, she loses her 100 shields, and take no damage on her white HP bar.
Add an internal cooldown until it can block damage again (preventing someone from, eg, pocketing Zarya and make her immortal), and add a 400 damage threshold, where damage beyond that surpass the shield blocking effect (so that Zenyatta can’t laugh at Self Destruct and RIP Tire). Maybe also add shield-bypassing effect on Widowmaker when she have Infrasight active.
And for the sake of consistency, rename Lúcio, Sigma and Doomfist decaying shields to “temporary HP”, so that it don’t have the burst-blocking effect. It’s already at a different color than natural shield.
The idea would be that armor is there to help with chip damage, and shield is there to help with burst damage. Two different mechanics to counter two different things, instead of trying to make armor the only passive defensive mechanic in the game.