This is an interesting comparison that tells a lot about the current economic structure of baseball. The Twins and Giants probably have a similar median value for the remainder of Correa's career - 35 WAR. What you're seeing is that 1 WAR is worth $8M to the Twins while it's worth $10M to the Giants (and more to the Mets). Neither team thinks Correa is going to be worth a darn at age 40 but the Twins don't pay the luxury tax so there is no incentive to spread out the years like there is for the Giants. The Giants probably would have made this a 20 year contract if MLB would have let them. The Twins will have to pay higher salary per year on shorter years to get top talent because time value of money makes that a more valuable contract for the player (8/285 is more valuable than 10/300 because $1M now is worth more than $2M ten years from now).
The Twins cannot afford a rebuild this season. They have a TV contract up for renegotiation. The White Sox are keeping their money in their wallet and the Guardians are beatable. Half of their pitching rotation (Gray, Maeda, Mahle) becomes a free agent next year. They have to try to win this division in 2023.
I agree that we are looking at a story of vastly different economic incentives for MLB teams. The large market teams want the playoff windfall so they will pay top dollar for free agents. Some of the small market teams will compete but only if it doesn't cost them much more than the minimum payroll (Guardians, A's). The mid-market teams (Twins, Cardinals) have to develop from within and are willing to pay for arbitration salaries or team friendly contracts signed when the player is under team control but can't afford top free agents.