Perception of the passage of time is linked to your memory. Think of it like this: If ten years passed and you have no memories at all from that time, then it's as if those ten years passed in an instant. What did you eat for breakfast two weeks ago? You can't remember because the brain doesn't record uninteresting events. There is only so much room there and it saves that storage space for noteworthy things. If you do the same thing every day without variation, like being stuck at home during pandemic, you won't have many unique memories from that time. Your perception of that time will be as if it passed very quickly. Compare that to growing up. Every stage of growing up is something new. You go to kindergarten, first grade, you go through puberty, making new friends. It's all new and noteworthy. It gets remembered.