These things (not just about bikes) come and go for me too. It seems normal, and as you hint, a bit sad to know that something once gave you a lot of pleasure but no longer lights up anything in you.
I think it has a melancholy in it because it's like seeing something that was important in your childhood, and remembering the feeling but no longer having it, and that's a recognition that part of your life has gone and won't come back.
I also think that the past 18 months have washed the light and enthusiasm out of many people for many things. For me, I'm hoping that some of those will come back when this all passes.