"from filter blur(20px)"   I figured gsap can scan that there is a number in this string and manages to tween this one number, as long as it is only one.  So I made a demo and tried it out. Variant 1: tween the element itself from filter: "blur(20px)" Variant 2: tween obj.val from 20 with custom function onUpdate.   To my surprise Variant 1 worked after Variant 2 was initiated at least once. Meaning Variant 1 changed to "fromTo" filer: "blur(0px)" > "bl