Same issue! After working for more than two hours on a text, suddenly, the page reverted back to an early time! I'm not sure if I pressed anything wrong! I tried the Undo but it only took me to what was even earlier...

I tried searching, looking for backups, and logging through the online OneNote, but nothing worked out... I'm very disappointed and I hope there's a solution to this, or at least know why it happens!

Microsoft® OneNote for Mac
Version 16.60 (22041000)

macOS Monterey
Version 12.3.1

Mac Pro (Late 2013)
Processor: 3 GHz 8-Core Intel Xeon E5
Memory: 64 GB 1866 MHz DDR3
Graphics: AMD FirePro D700 6 GB