(Not a balance discussion, if any of these changes are made it is presumed they’d be accompanied by other balance tweaks to keep her in a good spot)
I like how that lingering heal talent from Junkenstein’s Lab decouples Mercy from the pocket playstyle somewhat, though it’d be nice to have a visible gauge somewhere to see it build up/tick down.
Another idea would be for her heal beam to significantly boost a hero’s innate out-of-combat regeneration, rewarding Mercies who are aware enough to track which allies are about to start regenerating so she can take advantage of it as much as possible.