Hack goes on its full 8 sec cooldown when she takes any damage while casting it. This definitely did not happen after the health pack ult charge nerf patch. See in this video for example:
Watch at 10:12. He takes damage from Tracer while hacking, and hack doesn’t go on cooldown. This needs to be fixed because it’s such a massive nerf to Sombra who’s already really weak on this patch.
The Overwatch Classic patch is based on the September 2017 patch, the health pack ult change wasn’t for a few months later. She should have her health pack ult charge but she doesn’t
On a side note, her invis animation also breaks occasionally
Alright, I couldn’t find a source on what patch this classic was based on so I assumed it was after the healthpack ult charge nerf. Regardless, there was no point in history where interrupting hack put it on an 8 sec cooldown.
The description for Overwatch Classic on the client says “It’s September 2017, moths everywhere. Return to one of Overwatch’s most iconic metas” However, it seems you are correct that there shouldn’t be a cooldown on when hack is interrupted. They missed a lot of things with Sombra this Classic, it’s unfortunate