I’m not sure I’d say Tunsil is older, he will be 28 for the entirety of the 2022 season, or injury prone, last year is the only year he missed more than 2 games. And it was a thumb injury, I’d be more concerned if it was lower body or upper body. For me, neither of those are concerns.
But to your point on his salary - if he continues his level of play for the next 2 years it’s guaranteed he’ll command a large contract when his current deal is up at 2024 and with the Bengals needing to lock up Burrow, Higgins, Jonah, Boyd, Mixon if they stick with him, Logan Wilson, Awuzie, Reader or his replacement, I’m not sure the Bengals could afford to keep Tunsil.
And the Bengals don’t need an elite OL to win. They nearly won with the worst OL in the league. They just need to be like 20th, although better is obviously preferred.