not sure how to do it in unity, but in ue4 i’d most likely do that with mixing different textures together and then have them move creating movement. and actually you could do this in blender aswell.
create black and white textures or create procedural ones. that has different sizes of bubbles and other details you want, blend them all together with color inputs and then animate. in ue4 that would be panning the textures. also since i don’t know how unity does procedural textures, you might need to create those afterall.
