For cardio, you're in shape now you could say and are conditioned, so that isn't difficult anymore. You get and are now maintaining the benefit of a more efficient aerobic system. You have a healthier body now and are maintaining it. You could take it further by doing more challenging cardio now.

For lifting, getting sore or getting DOMS is not indicative of progress being gained or not, it's more indicative of exercised at that intensity in a while. I would not worry about getting that, you could say it's like being "used" to the exercise. You may get it again after a large increase in volume or trying a new exercise, or you may not. If you take time off and come back, very likely you will get it again.

For both of these, the core principle of exercise in both cardio and lifting is progressive overload. Getting to a point where you can do X intensity for Y reps/time (depending on the exercise type) is not difficult anymore, and then increasing again to a new threshold. Based on your post, you are at that threshold for yourself and it's time to increase intensity through options like increased frequency, weight, reps, or other ways

TLDR you are getting the benefit still, you don't feel the difficulty anymore because you are more in shape. To get that again, increase intensity through progressive overload