I (MBP M1 16GB RAM, BigSur) compared TBW result with my friend (MBP 2018 32GB RAM, BigSur).
for this "test" I made sure that Im not getting my SWAP used - and while I got ~20GB data written in one day just from other tasks I do, he got just 200MB written in 3 days!
so, based on this I would assume that the RAM is not solely a problem, but it adds its five cents to it.
what was odd for me, is that my TBW "jump" sort of matched what was visible in Activity Monitor data written summary (few gigs from kernel_task, few from launchd and few from my PHPStorm IDE), but in my friends Intel MBP case, his TBW reported by smartctl wasnt equal to what Activity Monitor reported (he had ~80GB in activity monitor, while only 200MB difference in TBW in smartctl between two days).
not sure to what conclusion this leads, but for me it looks like its not RAM that is the main cause, but its something else that either write too much to disk or maybe reports wrong numbers? (but whether its on M1 BigSur or Intel BigSur?)