Kenley Jansen settled for 1 year at 10 million and he's been consistently one of the best relievers in the game. Bummer is the definition of mediocrity. He wouldn't have gotten 9 million last off-season on a 1 year deal. This coming off-season, he would almost assuredly have to take a minor league deal if he were a FA.
Bummer is not a mediocre reliever and was coming off a 1.1 WAR season. He's had 5 full seasons (nobody counts 2020 and he was injured a lot of 2022) and has been worth 5.2 WAR in those seasons coming into this year. If he's only counting 6.5 against the luxury tax next year I'd say that's right at what you'd expect to get for someone like him on the open market.
The Braves do need a closer but they have several pieces already that can make up a good pen assuming we have a manager that knows what he's doing.