Had the same issue.
found a fix. Slightly annoying, but if you open the message thread with the person or group you had docs / pics / links history with and you click the top of the message on the name or “>” you should see towards the bottom of the “info” tab
”download ….. attachments”
***the “…..” above should be the number of attachments you’ve had in that thread. Attaching a photo. ***
to be clear - I have downloaded all messages from iCloud prior to this and you likely need to be on WiFi for it to work but I am not certain of that. I used this feature all the time on my 16pro and really annoying when it didn’t pop up after updating and getting air.
Hope this helps!
[Edited by Moderator]