Hi ,
Why don’t you use the UV0 channel of the custom UV’s?
Now the reason it is pixelated is because of Unreal using lower precision on mobile by default. Meaning it is not recommended to use high values as a UV input since it will look broken. So my guess is this pixelated effect comes from the fact you are using a Time node in the UV’s, which is for low precision fairly high after a couple of seconds. You could use a Frac before hooking your Multiply(Time, Speed) up with your Time input of the panner node.
Just to clarify what is going on. Frac will return the fractional portion of the given value. Meaning:
1,3 becomes 0,3.
0,8 stays 0,8.
Implementation could look something like this:
return value - floor(value);