I agree that the draft needs a third ban, but I prefer it at the start. It allows for more strategy from teams that actually study up on their opponents to block comfort/niche strategies from that team. It also has the benefit of being by far the easiest way to add them. They could do “honor-bans” in competitive almost immediately without any need to code them in, and it wouldn’t take long after that to add to HL and TL.
I like the idea of a second ban in mid-draft (ala your first suggestion) but I think that’s more appropriate for a future fourth ban, as it then opens the door for a ton of shenanigans in the draft that could force some significant adaptation from teams.