Can anyone with older Mac Studios/Minis comment - do you also notice a "throttling" of the hardware?

I'm not sure if this is me not maintaining it properly (e.g fans having dust block them) - but I've always got this sense that Apple throttles their older devices in some indirect ways. I experience it the most with iPhones - my old iPhone is pretty slow doing basic things despite nothing really changing on it (just the OS updating?)

So my only concern with this is - how many years until it's slow enough to annoy you into buying a new one?