Can't update mysql users authentication plugin in Google Cloud SQL because root does not have SYSTEM_USER permission

I'm working on upgrading my Google Cloud SQL mysql instance from 8.0 to 8.4. I just upgraded it from 5.7 to 8.0 and now I'm trying to convert my user authentication plugins for my existing users from mysql_native_password to caching_sha2_password so that I can take the next step of upgrading from 8.0 to 8.4. When I login as root, I'm not able to alter the various user's plugins and it gives me the error:

ERROR: Access denied; you need (at least one of) the SYSTEM_USER privilege(s) for this operation

I can't see any way to grant my root user that permission. I've got this list of users and I don't know how to update them before I perform the 8.0 -> 8.4 upgrade. I'm worried that I'll break a bunch of stuff if I don't update them before the upgrade to 8.4.

mysql> SELECT user, host, plugin FROM mysql.user WHERE plugin = 'mysql_native_password' order by user, host;
+----------------------------+-----------+-----------------------+
| user                       | host      | plugin                |
+----------------------------+-----------+-----------------------+
| cloudiamgroup              | %         | mysql_native_password |
| cloudsqlapplier            | localhost | mysql_native_password |
| cloudsqlexport             | 127.0.0.1 | mysql_native_password |
| cloudsqlexport             | ::1       | mysql_native_password |
| cloudsqlimport             | 127.0.0.1 | mysql_native_password |
| cloudsqlimport             | ::1       | mysql_native_password |
| cloudsqlimport             | localhost | mysql_native_password |
| cloudsqlinactiveuser       | %         | mysql_native_password |
| cloudsqlobservabilityadmin | 127.0.0.1 | mysql_native_password |
| cloudsqlobservabilityadmin | ::1       | mysql_native_password |
| cloudsqlobservabilityadmin | localhost | mysql_native_password |
| cloudsqloneshot            | 127.0.0.1 | mysql_native_password |
| cloudsqloneshot            | ::1       | mysql_native_password |
| cloudsqlreadonly           | 127.0.0.1 | mysql_native_password |
| cloudsqlreadonly           | ::1       | mysql_native_password |
| cloudsqlreadonly           | localhost | mysql_native_password |
| cloudsqlreplica            | %         | mysql_native_password |
| cloudsqlsuperuser          | %         | mysql_native_password |
| mysql.sys                  | localhost | mysql_native_password |
| root                       | 127.0.0.1 | mysql_native_password |
| root                       | ::1       | mysql_native_password |
| root                       | localhost | mysql_native_password |
+----------------------------+-----------+-----------------------+
22 rows in set (0.06 sec)

mysql>

How do I update these user entries so that I can safely upgrade to mysql 8.4 in my Google Cloud SQL instance?