Just submitted some diagnostics on my Apple TV.
Reported this bug some time ago but thought I’d report it again as it’s come up a couple times for me recently.
Was watching live TV and went to pip on my Apple TV.
Navigated to a show in the Home tab i am currently watching and pressed Watch.
It then changed the pip source to the tv show but only showed a grey screen.
When i went to full screen it was cycling through all the episodes for about a second and then moving onto the next.
I believe this has happened to me going from one show to another aswell. (Eg if i was watching the Simpsons, went into pip, then tried to continue watching Futurama - seem to get the same bug)