Currently SSR sets <html lang="en"> by default.
This is obviously wrong default as not every website created in Expo is in English. There should not be default lang attribute at all as It is not mandatory.
Replacing this needs creating whole +html which brings a log of boilerplate to the project just to remove default that is wrong by design.
Optional lang parameter could be probably a part of generateMetadata, so it can be easily set per route.