If you were building auth for Next.js today, what would you avoid?

I built MyAuth specifically for Next.js App Router with a server-first approach.

While building it, I noticed most auth solutions:
• Rely heavily on client-side SDKs
• Add unnecessary abstraction
• Feel bloated for small SaaS apps

Curious — if you were building auth from scratch today, what would you do differently?

Would love to hear real pain points.

— Deepanshu