The whole trick is to properly prep, then coat a frame (and/or parts). Then it WON'T flake.
I have three 'coated bikes that still look perfect 20 years on, with PLENTY of varied road-condition use.
I also know of over a dozen of my former clients' bikes that were properly coated, still 100% excellent condition, and regularly ridden.
Of nearly 100 client refurb/restorations, I NEVER received a SINGLE notification of failed powdercoating.
I will add - on two bikes that I later modified, I touched up the weld areas with Rust-O-Leum rattle can gloss black, and i challenge anyone to spot the painted bit.