The contract isn't horrible, though. Sure, he's probably a bit more expensive than he should be. He's making $27.5m and based on a $9m/WAR quick napkin math, he's probably right there. Add in the $5m buyout when he walks, and you can argue he's a few million too much.
With that said, the alternative is that the Cubs signed him to a multi-year extension at a lower AAV and he's signed for 5+ years longer.
The Cubs shouldn't have to eat a ton. Bellinger at 1/25m, especially for a team willing to play him in CF, is probably fairly decent value. That's eating like $7.5m. Ultimately I expect the Cubs will trade him. This is a combination of the Cubs standing firm on their value and the Yankees trying to use the Tucker trade to their advantage and squeeze the Cubs a bit from a leverage standpoint. It's just trade negotiations from both sides The Cubs did the right thing and got Tucker over the finish line, this deal be damned.