How to transition off custom database to cheaper plan

We started automatically migrating (trickle migration) our users to auth0 like a year ago. We now want to change to a cheaper plan (Essentials) which does not offer custom databases. At this point, we have no need at all for a custom database, but I have no idea how this transition is going to work.

According to this, you are just supposed to change the scripts to disconnect the store, but it specifically says " Make sure to leave the Import Users to Auth0 option turned on", and indeed if you turn it off, you will not be able to login with your users.

So what is going to happen when we totally lose our custom database? Will people still be able to login? Cannot find any info about this downgrade path.