YouTube picture-in-picture mode seems to be broken on Android and iOS, and Google is 'actively investigating'

YouTube's picture-in-picture mode is failing for a growing number of users on Android and iOS. When exiting the app, audio continues in the background, but the floating video overlay does not appear. Google has acknowledged the bug through a YouTube Help forum post, stating that their teams are actively investigating the issue. While some users are reporting the malfunction, the problem does not seem to affect all mobile users globally at this time.