Appreciate the quick reply and that you are investigating @robiub
Thanks very much for the help!
The issue is reproducible even in WordPress Health Check Troubleshooting Mode with all plugins disabled except Complianz.
Clearing only the Complianz cookies restores normal behaviour for the first page load. After the banner disappears, the cmplz_banner-status cookie is written with the value dismissed even though no consent action (Accept, Deny, Close or Preferences) has been taken.
This strongly suggests the banner is being dismissed programmatically rather than by an explicit user consent action.