Okay, this is a detail.
But it seriously bugs me. And if anything, it’s getting more common, not less.
a) Protagonist meets another character and thinks, right off the bat, that she looks like she’s twenty-one or he is probably about fifty-two.
There is NO WAY to judge some stranger’s age that precisely and accurately when you first see someone. It is IMPOSSIBLE for anybody to know know exactly how old people are when they just look at them for the first time. The author is providing special magic knowledge to their protagonist.
This goes for weight as well. No one can look at someone and just know she weights 152 lbs. If someone out there can do it, I still don’t believe in this peculiar talent when I encounter it in fiction.
I honestly am pretty darn sure I have never, ever done this. My protagonists always think “maybe mid-forties” or something like that. Sometimes they’re wrong, too. For me, this is an obtrusive mistake, one I really dislike.
b) Protagonist meets another character for the first time and knows how to pronounce and spell their name, even though their name is obviously not easy for the protagonist to pronounce or spell.
This isn’t as bad. But there are times when the reader isn’t going to be able to overlook it. If Bob steps through a portal and meets D’sanethalthi, he ought to stumble over that. If he doesn’t, again, that’s because the author is giving Bob special knowledge he really shouldn’t have.
c) The most modern variant, which I’ve seen twice this year so far: Protagonist meets another character for the very first time and, without a word being spoken and without any introduction of any kind, automatically knows this singular person wants to be referred to as they/them.
Authors. Seriously. Cut it out.
New pronoun traditions are one thing. Providing magic knowledge to your characters is cheating. It also implies that something is wrong with real-world people if they cannot tell by magic telepathy that a particular person they meet wants to be referred to as they/them.
Stop doing that.