I have set up a small cluster of three MariaDB servers synchronised via Galera.
Everything works perfectly, except for the fact that I can neither edit nor drop triggers from tables, once defined. The only way to get rid of a trigger is to drop the entire table, which – for obvious reasons – is a non-starter.
Even though my actual setup is bare-metal, I have put together an MWE running on Docker and exhibiting the same behaviour: https://github.com/fabrykowski/galera_drop_trigger_mwe
MDEV-21578 is similar, but deals only with "CREATE OR REPLACE" and not with "DROP".