This happens for example if one installs into home directory of a user
C:\Users\<username>\mariadb

The reason is that the service user "NT SERVICE\<service_name>" does
not have read and execute permissions for service executable mysqld.exe
in this directory.
Moreover, it would not have read permissions for server.dll loaded by the
exe, or to plugin directory, where plugins may reside.

The fix is to give service users read and execute permissions to bin, share, and
lib\plugin subdirectories.

The permission setting is doneby  mysql_install_db.exe, but also in MSI.
It is important to do that in MSI, as we want permissions to survive
the MSI upgrade.