With CVs/job applications? I guarantee you, if you'd actually do a real blind trial, you'd be wrong so often that you'd be embarrassed.
It does become detectable over time, as you get to know their own writing style etc, but it's bonkas people still think they're able to make these detections on first contact. The only reason you can hold that opinion is because you're never notified of the countless false positives and false negatives you've had.
There is a reason why the LLMs keep doing the same linguistic phrases like it's not x, it's y and numbered lists with Emojis etc... and that's because people have been doing that forever.