I'm a bit worried about my Squier J-bass.
I got it, after a few weeks, it needed truss rod adjustment, and ran out, so I added a washer rather than risk stripping the thread. Since then it's needed two fairly generous tweaks. Not sure if this is it settling in after taking all the tension off or something worse like the rod slowly crushing into soft wood at one end 😞
Be a shame if it does end up running out of adjustment as its a lovely neck.
String at one end on a bridge saddle, the other supported at the high point of a curved fret. If nothing else contacts the string what can affect it's vibration. Trignometry tells us differences in tension change with action will be (almost) negligible, as are any minute differences in break angle.
But I'm aware that every one of my basses feels different and I therefore play each one slightly differently, I argue this is where perceived changes in sound with action come from - higher action tends to encourage a more aggressive style and more staccato playing by damping with the left hand.
Obviously when strings start contacting other frets, that does make changes beyond just buzz, like introducing more harmonics if played hard.
Another variable could be if you fret very lightly/close to the fret so the string doesn't contact the fingerboard behind the fret (especially with jumbo frets, light action). I imagine this could reduce sustain and harmonic content.
Would be interesting for someone with a spectrum analyser to do an experiment.