https://wccftech.com/several-pixel-3-users-state-that-their-text-messages-are-missing/

Earlier this month, several Pixel 3 users reported photos taken via the camera weren’t saved at times. Google stated that they’re aware of the issue and a fix was en route. However, it looks like the November security patch may have been causing text SMS messages to disappear for a few users.

According to Android Police and several users on Reddit, text messages began disappearing from users’ inboxes shortly after the security patch was installed. One Redditor reportedly lost over two years worth of messages, with only recently created message threads showing up. Upon contacting support, several users were told that Google was aware of the issue and that they were working on it. It is unlikely that the Messages app is at fault, considering that older Pixels and the XL variant are free from the issue.