Never outsource your auth no matter what unless you're vibe coding and it doesn't matter. If that's the case, don't put auth in at all because it's just you anyway or just use vibe coded password lookups from database at that point.
Lastly - here's the law of mother nature:
Software funded by VCs will milk you and will milk you dry. Not now, not tomorrow maybe decade or two later when the hot potato being passed around reaches to the last party holding the bag that now needs its money back with all that others had their 10x returns already taken from them by soldng them at an inflated price to the last party holding the bag.
Clerk's pricing should be evidence enough.
You can literally plug the Better Auth libraries into a little Node server and run it as a separate auth server for free, forever, same as if you used a Django or Rails deployment for that purpose.
That’s all it takes to not use their cloud at all.
I'm not talking about open source libraries.