Is ther such thing as Custom UV shape (outliner fx)

Hello guys!

I’m trying to do one fx for a mobile game in UI.
So I have this banner and I want it’s outline to move like in picture

I tried it with rotation textures but it have distortion
Example with rotatin texture

I decide to creat my own UVs for that with help of blender

blue channel is mask

SO! This is what i achieved:

technically it’s right and has no distortions but the quality… let’s just not talk about it.

My Question is How can i creat such type of UV with good quality ?
Or should i do it in another way ?

Thank you all, and have a nice day

What mobile game engine are you using or what material shaders do you have access to?

Hi, I’m using unity, and shader graph