People not knowing about older, physical media. You know, tales of people not knowing what cassettes or even fucking CDs ARE? Oh my lord. Or of course, the classic "Hey, he 3D printed the save icon!" when a kid saw a floppy disk, lol.
Also, just hearing someone's birth year. After having nieces and nephews and just having met more people, it doesn't really bother me as much as it used to when I was a teenager (which is funny to me now). But I remember hearing people born just a few years after me and being like "that shouldn't be allowed." It still is kind of weird for me to think about how kids born in 2020 weren't really conscious during the pandemic, and are now 6 years old. Like no, 2020 just happened. 2015 was 5 years ago... what do you mean that we're closer to 2030 than 2020? Ew! Happens to me every decade.