user sysbackup in 19c?

Hi,

I'm testing Oracle database 19c (19.4) and I see that now most of the installation users, like sysbackup or sysdg, are created as schema-only accounts and the recommendation is do not change to common authenticated users.

But then my question is how are we supposed to use those users, because when I try to define a proxy connection i get

alter user sysbackup grant connect through c##test_conn container=all;

ORA-28154: Proxy user may not act as client 'SYSBACKUP'

Any suggestion?

thank you

Chiara