MySQL user privileges are not being respected in a local cluster

Hi, I am running MySQL instance with persistent volume from
https://kubernetes.io/docs/tasks/run-application/run-single-instance-stateful-application/
locally on my local docker cluster. When I create a new user it gets access to all the databases besides mysql one even though
show grants for my_user
returns
GRANT USAGE ON *.* TO 'my_user'@'%'
which means no privileges. No other grants that I give to the user get respected either.
However if I delete PVC from deployment all privileges do get respected.
Does anyone know why would using PVC cause such an issue?