The Samsung Galaxy Z Fold 4 inner screen has a problem and I got a replacement. Same phone. I can't transfer my messages from WhatsApp on the old phone. It seems my backup to Google hasn't worked for 5 months. I can't seem to back up. I select the backup feature, and it requests for me to log in to Google with my fingerprint. I do, and then I get a grey-on-white band with a backing-up sign, but nothing seems to happen. No spinning icon, just nothing.
I had to switch my WhatsApp back onto my old phone (which still has the messages). It also seems the Google account associated with WhatsApp on each phone may be different and I'm not sure how to adjust that.