数据库升级到19.18.0.0 后使用alter 修改源库的SYS 密码，备库端不会因修改密码中断。
参考 Doc ID 2307365.1
When password file is used for Redo Transport Authentication, the password of redo transport user should be same across primary and all its physical and snapshot standby databases.
By default SYS user is used to authenticate redo transport sessions when password file is used.
Till 12cR1 Dataguard setup, if there is a change in password file of Primary database like Changes in password or Changes in admin privileges, then the password file needs to be copied
from Primary database to standby database server and rename it according to standby database Instance name. If the password file of Primary and Standby databases are not same,
then errors will be seen.
In 12cR2, the password file of standby database gets synchronized automatically when there is a change in Primary database password file.
The password file change of Primary will be included in Redo and when the Redo is applied to standby, the synchronization happens in the background.
Exception: Far-sync Instances (where the redo will not be applied). We need to manually copy the password file. Once the password file is sync at Far-Sync instance,
the redo having password file information will get transmitted to standby which are suppose to receive from Far-sync instance.
