Growing cache with crawler entries when fallback:true

[gglnx]

My application has a /[lang]/[location] route. While [lang]/index.tsx is using getStaticPaths and uses fallback: false, [lang]/[location].tsx is returning an paths: [] in getStaticPaths and using fallback: true, because of large count of locations.

Crawlers for spam and security issues are probing different paths, like /wp-includes/wlwmanifest.xml. While /wp-includes returns an 404 error and will be not cached (.next/server/static/[ID]/pages), the request /wp-includes/wlwmanifest.xml will return an 200 status code (despite I'm returning <Error statusCode={404} /> if the location doesn't exist) and the request will be cached. This caching leads to an ever increasing size of .next/server/static/[ID]/pages.

Any idea how to fix the wrong status code and prevent caching of invalid pages, without setting to fallback: false and pre-render everything at deployment?