I don't know if this counts as a trope but I've been replaying Hitman 2 and the game has honest to god functional mirrors. And this was right before ray-tracing became really prevalent, so it doesn't kill the performance and it doesn't look like a blurry mess because of DLSS because the game supports neither of those things. As far as I can tell, they don't use the old trick of rendering the room a second time, either. And by functional I don't just mean clear, visible reflections. If you pull out a gun while standing behind an NPC, they'll spot you in the reflection and react accordingly.
It's just one of those things that games stopped bothering with so long ago that I've gotten used to mirrors in games just being some kind of weird-looking blurry surfaces. So when you run into one that actually works it's a nice detail. It's the kind of attention to detail that I've come to only expect from developers like Remedy at this point. I still remember when I found a projector in Control, lifted it with telekinesis and the image it was projecting on the wall reacted accordingly and even spun around with the projector. They're small, superficial details but I always appreciate it when devs actually bother to implement them realistically.