Are you on their startup plan that allows you unlimited "Enterprise Connections"?
I'd be very careful with how their pricing impacts your business as you increase your B2B clients with Enterprise Connections.
I'm honestly not trying to pitch you on anything, but when you outsource your auth* to a provider, you must consider the long term costs based on your business model and theirs.
We use auth0 at work and I've thought about it. With time given most users are SSO based, it's probably doable but annoyingly so over a month to move to another service. Not that we would want to.
Outsourcing auth is acceptable for saas customers. For consumer apps it's probably not a good idea, pricing models typically don't seem aligned in your favor for that.
I once did a migration of an auth system by having the new system attempt an auth against the old system if there was no password hash saved in the new one. If it succeeded, it hashed the password and saved it. Seamless for users.
Obviously the old system isn't going to stick around forever, but you can get a good chunk of the passwords migrated this way.
Especially since we have to handle b2b clients who have their own SSO, etc.