I believe before this season, the majority of injuries happened in the last 15 minutes of game. Or that that’s where the largest uptick was… Anyway. Those last 15 minutes were the largest worry for medical staff.
Now that we have an increased amount of time with the ball in play, that time frame will have changed for this season, and be earlier.
Ultimately, the total time for the game to take place isn’t the issue. It’s the amount of time the ball is in play. Which has gone up, as that was the point of the rules changes around time wasting, and how extra time is calculated.
Some of the blame also falls at the feet of team owners and managers. Ultimately, a team isn’t forced by FIFA or UEFA to always start their best 11. But when you want to win every game, you will always put out the team that you feel gives you the best chance of winning every competition you compete in.
Managers could just play youth players in the cups, get knocked out early and then not have to worry about it. But they want to win, the fan’s want to win, and the teams want to make money.