When you have HA configured, you can edit the configuration through the interface. But with the new backed roles, some previews configurations are now backed by the database. This means that the can be editable anyway without interfering with the HA. Actually, can an still save them in the admin interface, but if you save them, you see an error trying to save the config file.
Expected behavior: You only see an error saving the configuration for fields baked by the config.json file.
Current behavior: Independently which fields you edit, you will see an error message message that you can't edit meanwhile you have HA enabled.
It can be tested enabling HA, and trying to change in the policy page the banner information. It must fail with the fields edited. Other test is change any of the fields nod related to banners, and it would work without failing. The third test is to change banner information and other fields, and see if there is an error which list the fields from banner information that fails. (Actually is not banner information, is config based fields (the banner fields), and permissions based fields (almost the rest of the fields)).
Take care, when you enable HA in the interface, after that, you can't disable it through the interface.
Verified on selenium.mattermost.com on 4.9.1-rc1 that without HA enabled I can edit the banner settings as expected. Verified that with HA enabled, I see the expected error message specifying the field(s) when trying to edit banner settings. With HA enabled, I can edit policy settings as expected. Closing.