Anyone Can Register

It simply allows the general public to create a new WordPress user. Whether or not they can see other user’s user information depends on the default role assigned to new users and any capabilities assigned.

Unless you change the default role setting, new users will be assigned the Subscriber role which only has the read capability by default.

The read capability only grants access to an almost entirely stripped down dashboard screen and their own user profile.

You can refer to this table for the default roles/capabilities assignment. In general, any role below Administrator cannot access the general Users screen in the dashboard (or the /wp-json/wp/v2/users REST endpoint) for not having the list_users capability.

Try it yourself: create new Subscriber user through the dashboard, then log in as that user and see what you have access to.