What do you check before launching a web app?

I’ve been reviewing a lot of small SaaS, indie, and AI-built web apps recently, and I keep seeing the same pattern.The product often works. The landing page looks decent. But the boring launch-readiness basics are missing.
Things like:
unclear positioning above the fold
missing security headers
weak or missing privacy / terms pages
no obvious trust signals
poor mobile experience
basic accessibility issues
SEO metadata that has clearly been left until the end
exposed implementation details in client-side bundles
APIs that look like they may not be properly isolated or proxied
I’m curious what other people here check before they consider a web app “ready enough” to put in front of real users.
Do you have a personal launch checklist?
And for people who review a lot of early-stage products, what are the most common issues you see?