Is there a name for this - when the sound of a synth preset changes as you play

[bill5]

I noticed that sometimes when I'm trying out a preset, the more of a legato approach you take, the more the sound changes (some more than others), typically becoming less pronounced (I can give examples if it helps, but not sure what soft synths anyone has). 

[CyberGene]

It’s called envelope re-trigger. Or in this case the lack of it when playing legato. More specifically, it’s the filter envelope that opens the filter on attack and then decays to a soft sustain sound. When envelope re-triggering on legato is switched off, you would hear the new note without a filter attack, only playing at the current sustain level which might be low, hence a closed filter and a softer timbre.