@TeamYouTube I don’t know why but sometimes when videos play and I have it at the bottom while going through videos, when I put it back to full screen it shows a thumbnail that’s not even the same video instead of the video itself (this only happens on my phone)
That doesn't sound right, if you haven't already, try reinstalling the app. If that still didn't work, we'd like to request for more details you can share about the issue here: https://yt.be/help/feedback . This is to help the appropriate team further investigate.