WhatsApp (released on 25/05/2021) does not restore from local backup. We're trying to understand if it's just a temporary issue.

In order to fix this:

  1. perform migration as usual using older WhatsApp 2.18.248, then uninstall it
  2. when requested to update WhatsApp, install pre- WhatsApp release downloading here or from APKMirror. This is because Play Store provides latest version only

Next WhatsApp updates will come automatically through Google Play Store.