A few years ago, a YouTube update changed the video player's progress bar, extending it over the full width of the display. Ever since, it's been easy to miss the fullscreen button and hit the end of the seek bar just below it instead, often making for a frustrating experience. A YouTube app update tries to remedy that problem by preventing the bar from responding to single taps at all — you now need to hold and slide your finger to seek.
If that seems familiar, this behavior is default on the iOS YouTube app and also first surfaced on Android back in 2018, when YouTube said it was an issue that it eventually fixed. It looks like the developers have now decided that this behavior is actually beneficial to avoid frustrating accidental scrubs on Android, too. Silver Product Expert rjlefty96 shares in a few Google Support threads:
Q: Why are you changing the seek bar/progress bar/scrubber experience? / I can't tap to move the seek bar/progress bar/scrubber for some reason.
We heard that a single tap to move the progress bar caused a lot of frustration with accidental taps. Now you can tap, hold, and slide the progress bar -- the red dot will track your movement and once you lift your finger, the video will jump to that point in the video.
We couldn't find this FAQ entry in any publicly available Google support documents, so we assume that the Product Expert has access to internal documents or is in contact with a Google representative. They further explain that previously
on Android, users could tap anywhere on the seek bar to jump to that point in the video, and on iOS, users need to tap and hold at a point on the seek bar to do the same. The new experience will be the same across Android and iOS, where users need to tap on a point on the seek bar, make a horizontal scrubbing gesture with their finger in order for the scrubber to jump to that point in the video, and once the user lifts their finger, the video will jump to that point as well.
The new seek bar behavior makes a ton of sense on paper, but it seems buggier than the 2018 version. When you tap to seek, the video buffers for a second without losing its current position. There is also no tutorial or indicator alerting you that you can no longer tap to seek, which would've helped understand that it's not a bug but a feature.