Is build-to-rent overbuilt in the Sunbelt now?

It's submarket-specific, which is the whole answer. A few Sunbelt submarkets are genuinely oversupplied on BTR for the next 18-24 months — you can see it in concessions. Others still have years of runway.

Don't underwrite 'the Sunbelt.' Pull the permit pipeline for your specific submarket and overlay it on net migration. Where the pipeline outruns migration, sit out a cycle.