That’s usually a combination of planned obsolesence and bad software, Smasung flagships for example start to significantly slow down after roughly a year of usage. These CPUs are more than enough for daily tasks like web browsing and as soon as you have a manufacturer with good software support or load something like LineageOS on the device it usually works very well again, in some cases you also need a new battery because many clock down once that looses capacity.
That’s usually a combination of planned obsolesence and bad software, Smasung flagships for example start to significantly slow down after roughly a year of usage. These CPUs are more than enough for daily tasks like web browsing and as soon as you have a manufacturer with good software support or load something like LineageOS on the device it usually works very well again, in some cases you also need a new battery because many clock down once that looses capacity.