When backupping a large MyISAM table alongside smaller InnoDB tables (for instance), there will be regular outputs of "InnoDB: Read redo log up to LSN= ..." and "log scanned up to (...)" during backup of the large files. Since InnoDB backup is finished, this is always the same value. Ok, if there are new entries in the table during backup, it would make sense to report that. But otherwise this just clutters up the output and leads to the conclusion that mariabackup might be stuck.
Edit: Other users DID conclude that mariabackup is stuck, i.e. here:
MariaDB ServerMDEV-26984
Because of that I changed my priority to "High".

Please remove/suppress InnoDB log message, if no new LSN has been reached. That way the last seen entry is the large table, which makes more sense. If you want to show activity, rather add a percentage output for large tables.