As mentioned a number of times now, the WP Discourse plugin does not, and has never, supported using Discourse as the DiscourseConnect provider on multisite instances.
Moreover, the way DiscourseConnect (previously SSO) works in WP Discourse has not changed for some time. There is nothing to roll back to.
I’m sorry, but If you have issues on your site that you’ve created by somehow trying to attempt this configuration (how, I don’t know, as the tab is not available on multisite instances) you’ll need to either resolve it yourself or hire someone to do it.
We don’t, and have never, supported using some kind of workaround for using the plugin in this fashion.