Could also just be software updates or other things causing this but there should be some component of decreasing performance caused by wear on flash storage.
Could also just be software updates or other things causing this but there should be some component of decreasing performance caused by wear on flash storage.
A lot of - especially older or mid/low range - phones have cheap eMMC storage which is signifcantly worse at wear leveling than the higher end UFS storage.
Which is shocking really - the phones should switch the eMMC to RAW flash mode (ie. no wear levelling), and then write an actually-smart wear levelling algorithm that runs in the OS.
The OS has far better info for wear levelling anyway - it has more visibility into read-write patterns, it has more RAM to store more state, it can cron background scrubs and reorganisation to idle periods, it can be patched if a bug is found which only manifests after years, etc.
Unfortunately, as far as I'm aware, most eMMC's can't be put into any kind of RAW mode anyway.