After verifying with both the pixel 4 and iPhone 11, the new gesture navigation system is indeed not optimal. On both the pixel 4 and iPhone swiping up and then down from the bottom "triggers" and then "untriggers" the multitasking view, returning you to the app at hand. On One UI beta this sequence forces you to stay in multitasking view. I hope this is simply a bug that will be addressed in a future update.
