iCloud backup for messages for only One year back ?

Hi,

I had an issue with my IPhone XS which requires to be dropped at Apple to check it. I made a backup of the phone in order to transfer my data to my other IPhone 7. After restoring my backup from iCloud to iPhone 7 is finished, I can’t see all messages. The oldest message was Dec 2019, but I have very important messages since 2015 but I can’t find them.

Can someone tell me what to do, I NEED MY OLD MESSAGES PLEASE