I'm nowhere near that level of experience, although I've done both as well. I'm more backend oriented. And my experience has been the opposite. When I ask for backend code, footgun after footgun appears on my screen. With frontend code, much less of an issue, as far as I can tell. Part of me believes this is because I'm less skilled at frontend, and I don't bat an eye when the LLM plops down yet another useMemo (I've since learned that this is rarely needed). But in your case this argument can hardly be made. With 25 years I trust your ability to spot a good design on either end of the stack. So then I don't know where this discrepancy comes from. Maybe my prompting skills leave something to be desired.

I don't do "megascale" backends, though. My code is generally smaller-scale stuff that's designed to be deployed on a wide variety of cheap hosting, and is pretty conservative. It doesn't "push the limits."

I'm unlikely to run into many of the problems that (for example) the PornHub developers hit, several times an hour.

In that case, I benefit from folks like you, that allow me to have solutions that scale down to my level.

I wonder if it's expertise gives you ability to see flaws and push the LLM past its acceptable point.

I haven't really used LLMs much for coding (sabbatical before LLMs got good at coding, now looking for work) but I found with chats that they are great at exploring well trodden territory but as soon as you go a little bit off the beaten path they flail horribly