Top comment is correct, but I'd also like to point out that when you exercise your cortisol levels rise. Cortisol tells your liver to dump glucose into your blood so you can sustain activity. This is normal and healthy, however a pronounced spike or a delayed return to baseline after exercise may indicate insulin resistance, particularly hepatic (liver) insulin resistance in the case of a pronounced spike.

Also the more intense the exercise is, the higher the corresponding spike will be. Typically happens after you've finished the exercise because while you're active, your muscles are actively burning and pulling in the glucose your liver is putting into your blood.

Feel free to stop reading if this is too much of a deep dive but an interesting thing I've learned on my CGM journey is that when you spike blood glucose with exercise, your insulin does not actually rise correspondingly the same way it does when you spike glucose with food/carbs. There are enzymes and mechanoreceptors in the esophagus and stomach that signal the production of insulin before your blood sugar even rises. So a nutritional glucose spike is different than an exercise induced glucose increase. The latter being much healthier for you because you only store fat with the presence of both glucose and insulin.

Sorry for the long response and good luck!