It looks like the liner is torn around the return jet.
Although I don't have a lot of experience patching liners, if it were me, what I would do is drain the pool to a few inches below the leak. Then remove the return from the pool, and apply a patch that is 1-2 inches bigger than the hole for the return jet and leak, then apply a second patch 2-4 inches larger than the first patch. Once this is done, cut and re-install the return jet.
If you don't have any liner material, most pool stores carry pieces of their liners,,,,,, just don't let them test your water.