Every player takes plays off. It is a long grueling season, and they are playing at arguably the height of athletic play in all of sports for extended periods of time. It does not let up. Human nature takes over at some point and they conserve energy. It takes a concerted effort to push past the body's desire to rest and get the last of the endurance or power the muscles have to offer in a lot of these games. No wonder they take plays off.
I was never a world-class athlete, but in high school I could get up and down the court without being winded much, and could dig deep for a push at the end of a tough game. One of the 3 dunks I had in a high school games came near the end of an OT game when I and 2 other guys had played all but something like 3 minutes of the game time. We had a breakaway and I went up and technically had a dunk (the ball cleared the rim, I followed it and pushed it through the hoop with my hand on top of the rim. That's a dunk, right? LOL I could not palm the ball so that was my only option). I was thoroughly exhausted at that point, but I got one more big jump out of my tired legs and it was cool and a lot of fun and gave us like a 6 point lead or something. We ended up winning. Then I went home and ate like 4 plates of spaghetti my mom had made (she makes great spaghetti), and then I slept like 14 hours.
I cannot imagine the physical strain on these guys at this level. And for that many games. The 20-odd games we played in HS with the tournament and all were plenty for me. I felt like I was tired all the time, I could eat like a horse, and my muscles felt like jello a lot. What must it be like to be working at the level of a Donovan Mitchell. Insane. So taking plays off is not a surprise, especially at the end of an intense game. It takes serious mental fortitude to push past your human physical endurance levels and squeeze out that one last burst of speed or power to make that big play. Frankly I am surprised we don't see more of them take plays off like that. Of course, that is the different between us basic HS or even college players and the pros. Frankly, it is awesome to watch.
