@davenothereThis sounds like a story I just read recently, but I can't remember the title or author. I'm not even sure it was on here or if it was on Kindle Unlimited. If the story I'm thinking about is the same as you, the scene you describe is when the MC is traveling to return a princess that was kidnapped/detained back to her father. They are stopped over in a town near the border and staying with the guy in charge of the town. The MC is in the prized garden of this guy and is practicing his ability to speed up his reflexes so he sees things in fine detail and slow motion. He starts just slicing a leaf off a plant and ends up doing the same to all the leaves, leaving the garden a mess. I think this is about 1/3 of the way into the story, but I'm not sure.
I know it's not much more to go on, but I hope it helps.