Short answer, if Bakhtiari retires or get released before 2024 season, then Packers automatically free up $21.7 million for 2024.
It can be more than that with Packers automatically a prorated part of his $1.2 million 2023 base salary. (Like there are 14 weeks left, so if he did it right now, Packers would get 14/18th of the $1.2 million).
Also most players keep their mouth shut during the season unless they have received agreement from the team that the team won't go after their signing bonus, or force the team to release them, so they get to keep their signing bonus.
In theory, if Bakhtiari retired, the Packers could go after Bakhtiari forcing him to repay $6 million in signing bonus for 2024, and a prorated amount of an additional $6 million for 2023.
Again, he'll probably won't say anything until after he gets the Packers to agree they're not coming after that in legal writing, unless he wants to give it back.
So in total, it'll probably be near the very bottom of this range, but we're talking $21.7 to $33.3 million for 2024.
If you mean for just 2023, then likely less than a million.