mrXmr the column is called is_email_confirmed in the current Flarum version (1.7), but it's just the attribute storing whether a particular user was enabled. It's not a Flarum global setting.
Once a user email was confirmed, Flarum does not expect the value to go back to 0. Doing so could lead to issues. To disable a user after it was already enabled, it should be suspended using the Suspend extension.
The extension you have already commented on does what the previous commenters were hoping an extension would do, it sets the value to 1 automatically for every new user https://discuss.flarum.org/d/6485-email-verification-switch