I find my memory is very selective. I wanted to get in touch with a coworker from five years ago: I had to look up his name on linkedin. My wife texted me "Hotlips died" and with no effort I texted back, "Oh no, Loretta Swit or Sally Kellerman?" Mind you, I haven't watched MASH the TV show in forever, and I haven't seen MASH the movie since my parents took me when it first came out. I have zero reason to remember Loretta Swit, let alone Sally Kellerman, but my brain hangs onto that like it matters; but a guy I worked with for two years five years ago, that my brain will drop like it's radioactive.
Yeah this matches my experience too. I noticed this in Anki. Some cards are effortless, some take a bit of practice, and some I fail over and over again no matter how many times I practice them.
Anki kept flagging my relatives birthdays as "leeches!"
I found it kind of hilarious and infuriating that the software I used to remember things tells me "this thing is hard for you to remember so you should just give up."
Isnt that kind of like older memories get a strong imprint -- as you get older there are so many memories in the database that the imprint isn't as powerful as earlier ones. I think it works kind of as a function of kind of sensory component of memory implying that new memories aren't new to you therefore less powerful (obviously high variance and person dependent).