The mariadb man page does not specify that --defaults-group-suffix= is only recognised when it is the first argument. (The other two --defaults-... options do correctly specify this in the man page.)

Additionally, in the output from mariadb --help, the options --print-defaults and --no-defaults are preceded by:

"The following options may be given as the first argument:"

Perhaps "must be" would be clearer than "may be"?

Whereas the --defaults-* options are preceded by:

"The following specify which files/extra groups are read (specified before remaining options):"

Perhaps this could be said better as:

"The following specify which files/extra groups are read (must be given as the first argument):"

I found these issues in 10.6.15 and 10.6.16, but I assume later versions are also affected. Or at least I can see the issues with mariadb --help in the container version of MariaDB Server 11.3.0.