Does it work if you use non-transparent color?
Your code is wrong as the Touch event can be called many times. Change the animation to happen only when Action = pnlX.ACTION_DOWN.
Changing Colors.Transparent to Colors.Blue does goes straight to blue without animation on the S10 only
ACTION_DOWN is always 0 on the Samsung Tablet and S10 phone as I touch the panel.
I tried pnlX_Click event, and this does not fire either on the Samsung Tablet or the S10