Why is my playback button gone on my wireless camera's?

Your camera WVOD1 is a Version Once Battery powered WYZE Cam Outdoor and it has never had playback from the bottom of the screen. I have been using the same cameras since 4 November 2020 and they never ever had playback as you described.

WVOD1>>>

Playback from a plugged in powered a V3 camera >>>>

This is the events page on the WYZE app >>