iOS doesn't let users pick which app handles a custom URL scheme — first app installed wins. So with both Primal and Clave registered for nostrconnect://, Primal wins on most iOS devices where both apps are installed.
If you want to support Clave specifically, I made a universal link. Using https://clave.casa/connect/?uri=<URL-encoded nostrconnect URI> will allow for deep links to clave. Not sure if primal has a universal link as well.
https://github.com/DocNR/clave-casa/blob/main/docs/integrations.md
