It does its job excellently. The pool had two small holes, which we discovered after filling it. Because we didn't want to empty it (and waste 20 cubic meters of water), I tried applying the patch to the pool while it was still full.
Do not attempt to apply the patch externally, even if the flow is small, the pressure is very high. I dove in and stuck the patch to the hole inside the pool, while another family member pressed with their finger from the outside to help me locate the spot. The patch stuck immediately despite the fact that the adhesive side had briefly gotten wet, and the water pressure keeps it attached until today.
Lastly, don't be deceived by the yellow color, the patch is transparent and practically invisible. The packaging contains 10 self-adhesive patches.