I looked into Auth0 (and some competitors) a few years ago, and eventually figured out that, outside of a narrow usage band, it was extremely expensive given th

I looked into Auth0 (and some competitors) a few years ago, and eventually figured out that, outside of a narrow usage band, it was extremely expensive given the not-trivial nature of integrating it and its various downsides. So, compared to implementing an OSS auth server/framework yourself, it just didn't seem worth it.