I think that everything is experienced differently when you are a child because of the sensation and feeling of novelty, this makes the brain generate a lot of dopamine and serotonin, every time you embark on something new or try something new you have a similar feeling but perhaps not as powerful as when you were a child, for what I have no explanation is for the most vivid memories as you age.

Because adulting sucks

I feel a lot of memories from my childhood have faded. Only the ones worth remembering are recalled. But I have heard before that every time you recall it, you change the memory a little bit. Change its perspective, which could change the whole narrative of that memory.