The last 12-18 months or so I've started to realize that I'm having a harder time reviewing code, especially if that code is from a stranger (e.g. on an OSS project) or a new colleague.
I find that I will take a first glance at the code, notice the inclusion of some more advanced concept or technique, and instinctually I'll assume the code is the product of a more seasoned developer. Then, quite often, I'll come across something in the code that doesn't make sense. My initial reaction is to assume the author of this code is using some new technique or approach I'm not familiar with. I'll dig and search and turn myself inside out trying to figure out what I'm missing...only to eventually come to the conclusion that I haven't actually missed anything.
No, the reason the code didn't make sense to me is because the code just...doesn't make sense. It was not the product of some seasoned developer, but rather of a junior developer who has simply made a series of run-of-the-mill junior-developer-mistakes. In the past I would have been able to pick these sorts of mistakes out from a mile away. Now I find I have to see past the patina of pseudo-sophisticated LLM-generated code first before I can start the review process.