Old messages disappeared from iPhone and iPad

Hello everyone. I recently noticed that for some strange reason I lost all messages (iMessages and sms) dating back to 2017. I don't know exactly when it happened, I noticed it a couple of weeks ago. Until this summer I'm sure there were. I tried to disable Messages in iCloud, to download the messages to the iPhone and I notice that if I go to Settings - iPhone storage I can see the attachments (photos and videos) that are older than 2017, but they still don't synchronize in the respective chats (as you can see from screenshots).

It's strange because the space occupied by messages on iCloud has remained unchanged. It's as if those messages were still on my cloud storage but iCloud can no longer synchronize them across devices. I contacted Apple support, but they told me that without an old backup it is impossible to recover them.

How could this happen? Are there solutions?