Start by applying a nice gradient to the background layer.
Create a "6 point star" shape using custom shape tool.
Change the layer mode to "Luminosity".
Similarly create more star shapes and play around with their layer modes.
Create a circle using the elliptical shape tool. Hold on Shift key and create circles as shown in the image below. Create circles way out of the vertical boundaries as we'll create a bubble motion out of them.
Double click the layer to open layer style window. Apply settings as shown.
Change the layer mode to "Soft Light" and Fill value to 0%.
Similarly insert more shapes to create a complex background.
Open animation window. For the first frame move all objects beyond the edges. Align the top edge of bubble layer with the top edge of the file.
Duplicate frame. Move the bubble layer upwards. Move all other objects to the opposite directions and again out of boundaries.
Click tween button from animation window. Apply settings as shown.
Press Ctrl+Alt+Shift+S to save an optimized animated GIF.
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