To complete the installation, some lately quite common use-cases would require host part of the database username to either be overridable or the set of options to be extendable.
A minimal desired outcome of this would be if you added subnet C wildcard option to list of possibilities based on the resolved database id (i.e.: 172.16.1.%).

To simplify the use case, imagine having a docker setup with multiple containers:
http server (nginx), php processor (phpfpm), db (mariadb)

If i let the installer create database user for web access, it creates users with multiple hosts (IP, 'localhost', 'localhost.localdomain', '%') of which only the wildcard works as db is not on the same IP as php processor, but using such wildcards is undesirable in certain data centers.
If i manually create the user, the installer dies (error 1133) when granting privileges.

At the moment the only workarounds i have for this issue is to let the installer create the user and then do the cleanup or if i have a pre-existing user (usually for shared setups) is to change it's
host specification to general wildcard for the duration of the installation.