what does this error mean?

[17:02:13 WARN]: [me.lucko.luckperms.lib.hikari.pool.PoolBase] luckperms-hikari - Could not validate connection me.lucko.luckperms.lib.mysql.jdbc.JDBC4Connection@2e943928 ( No operations allowed after connection closed). You might consider using a shorter maxLifetime value.

Typically your maxLifetime value needs to be shorter than your MySQL server's wait_timeout. You can read up more on the error here: https://github.com/lucko/LuckPerms/wiki/Storage-system-errors#mysql-no-operations-allowed-after-connection-closed-error