It's not possible to do EXPLAIN's on the replica databases:
MariaDB [nowiki_p]> EXPLAIN SELECT page_id FROM page WHERE page_id=1; ERROR 1345 (HY000): EXPLAIN/SHOW can not be issued; lacking privileges for underlying table
According to https://bugs.mysql.com/bug.php?id=64198 this is due to missing the "SHOW VIEW" privileges. Is this possible to be part of the default privileges?