WhatsApp backup overwrite

***Similar issue reported but no responses*** I am posting here for more visibility

I recently had to reset my device at Apple Store. I had taken all data backups specially WhatsApp on my iCloud (excluding photos). After transferring my data, when I opened WhatsApp on the new device, it asked me for my phone number and then to set up a new password for my backup. It didn’t offer me to reinstall my old backup. After entering a new password, I received notifications for the groups I had been invited to. But nothing else. No old chat whatsoever.

When I went to the settings to check my backup it was a brand new backup with no data. I had nearly 3GB of conversation from the last 10 years which were really important to me.

My old backup must still be stored somewhere and I cannot believe that in 2023 it cannot be accessed by anyone. I have already tried reinstalling several iCloud old backups without any success. Even an iCloud backup from June returns the WhatsApp backup from yesterday. I don't understand how it can be. I did everything by the book and trusted Apple to save my data properly. But it doesn't seem to be the case.

Did anybody encounter the same issue? Would you have any suggestion as to what I might try? I had my phone backup via iTunes on my laptop, would that restore work? Likely erase my latest conversations.