Firebase Login Demo
This is a minimal, reproducible example for sign-in link issue on iOS Gmail app.
master
branch has a working example with Google-provided domain (firebaselogindemo.page.link) being used in "sign-in with email" links.
custom-dynamic-links-domain
branch uses a custom domain (firebaselogindemo.rkb.io) for sign-in links. Sign-in links generated using this domain doesn't get recognized as dynamic links when opened from Gmail app on iOS.