Can't restore messages

I replaced my phone a last week, unfourtnatly I couldn't restore any of the local backup from the old phone, but I still have a backup from Google Drive last updated in March. I try to restore it but I keep getting the same error message. I showed it to the guy from the phone store near my house and he said he saw the same error with few other customers and he thinks it will be solved in days, but almost a week has passed and I still can't restore my backup. I try to seek help with Whatsapp's technical support on email but their answers don't help. Anyone has any advice? I'm really quite desperate.

Thanks for your reply, I just tried both things and neither is working. I'm getting the same message.
It's weird that whatsapp don't show the backup file size at all. Is there a chance there's problem with the backup itself?

Thank you, I tried both using wi-fi and cellular data, and also made sure several times my Google account is right, I've enough storage etc. I really can't find the reason the restoration fails.

Yes, cache and data