I just switched my wife's phone from a Pixel 4a to a Pixel 8, and used the USB cable method to copy data. Prior to initiating the transfer I forced a backup of WhatsApp chats to Google Drive.
However, the entire transfer process took over an hour, during which time new messages came in to the old phone. The entire history with the exception of these new messages appears to have restored to the new phone.
Is there any way to recover and transfer these last few messages from the couple of past hours?