Нашёл 6 млн ответов for 'pop up sound'.
https://www.soundsnap.com/tags/pop_up
https://www.soundsnap.com/tags/pop
https://www.soundsnap.com/tags/popping
https://www.zapsplat.com/sound-effect-category/pop/
https://www.zapsplat.com/sound-effect-category/pop/page/4/
https://www.zapsplat.com/sound-effect-category/pop/page/2/
https://www.myinstants.com/instant/pop/
https://orangefreesounds.com/pop-sound-effect/
https://www.storyblocks.com/audio/search/sound+effect+pop+up
https://www.storyblocks.com/audio/search/pop+up