Its comparing Sombra to the Spy isn’t a fantastic idea, but I do think there’s some important things to compare when you think of the two. Namely, the spy has always had a more flexible options on his cloak, but he has no ability to quickly teleport if his flank goes wrong.
Even with custom weapons, you’ll notice people will give him a teleport or jump option at the expense of his cloaking. They’ll either remove it entirely, or make the cloak weaker to compensate.
With that in mind, maybe it was never infinite stealth that was the issue for Sombra? What if it was her ability to escape after things go wrong? What if she could cloak forever, but she was more committal due to a lengthy TC cooldown or now TC at all?
Forgive my ignorance on this; I’m mostly going off of what I see when playing against Sombra, or when I see professional sombra players play.