I don't think I've ever regretted overdesigning to meet a common standard or match how everyone else does something.

A lot of the YAGNI I see is in the form of "We don't need a framework, just do vanilla JS" or "I only need one of the features of this library, I'll just write it myself".

Almost all of my own big tech regrets have to do with building something "innovative". Even when they've solved the problem better than existing solutions they often become regrets, just for the simple fact that they aren't better by enough to justify the nonstandardness.