Three short lines carry a quiet unease about time. The speaker feels youth is "sneaking up" on them, which is an odd phrase, since youth is usually something you leave behind. It suggests the speaker is only now noticing what youth was, or how much of it they have, just as it begins to go. Then comes the final line, which states it plainly: "All my youth is fading."
Alongside this, the speaker sees "older generations slowly disengaging." The people who once seemed to anchor the world are pulling back, perhaps through age, distance, or loss. The poem doesn't say which. The word "slowly" appears twice, and that repetition makes the change feel steady and unstoppable.
The mood is wistful and a little anxious, without drama. The speaker doesn't complain or explain, just observes. That restraint leaves a feeling of being caught in the middle: watching those before them step away while their own younger self follows.