I suggest fretting slightly behind the frets not on them, and trying to lift your fingers off more swiftly and cleanly. The slow release right over the fret is the cause and I can duplicate it here.
It's easy to address fretting position, a little further behind the fret will do. Learning a clean release will take a little more effort.
A good exercise is to play a series of staccato notes, not too fast, lifting your fretting finger between them but leaving it very gently in contact so it mutes the string. Keep practicing until you can get a series of clearly defined and separate notes.
This will help you learn a clean, fast release and also start to develop the prized skill of muting.
Good luck!