Same issue since I used plex years ago, and problem is lasting now (server version: 1.25.5.5492 on debian bullseye / plex web version: 4.69.1).
This problem may concerned with the bug: [BUG Identified] Photos Library - Photo Library Timeline Not Working - #13 by ben-page
because wrong date issue occurs on older photos rather than newer photos.
And analizing library was not solved the issue.
I hope to fix this bug, really… TIMELINE IS CRITICALLY UN-USABLE.
