Nonsense error "alter routine command denied"

The server reports an access error when it is expected to do nothing.

Server version: 10.6.5-MariaDB

\utest

DROP PROCEDURE IF EXISTS THIS_PROCEDURE_DOES_NOT_EXIST;

ERROR 1370 (42000): alter routine command denied to user ''@'localhost' for routine 'test.THIS_PROCEDURE_DOES_NOT_EXIST'