MariaDB Docu about mysql_upgrade seems to be partly wrong:
mysqlcheck --no-defaults --all-databases --fix-db-names --fix-table-names --write-binlog
mysqlcheck --no-defaults --check-upgrade --all-databases --auto-repair --write-binlog
mysql_upgrade --help states that write-binlog is false.
So this is a discrepancy. Either docu is wrong or --write-binlog is not completely considered.
Our own tests with general query log show that there is NO write to binary logs while mysql_upgrade. So utility is correct but docu is wrong imho.