[Routing/SEO] duplicate content when add .html to a kirby route

If we add .html to a kirby route, the site is shown, but i would expect to see a 404.
Unfortunatly i get an issue in google search console.

See the examples below:

Can we avoid that?

You could use a route that disables such URLs. However, I don’t really see a problem here SEO-wise, because this URL shouldn’t appear anywhere? Or do you have old urls ending in .html flying around?

Having said this, someone else reported a similar issue: .html pages showing up in analytics - #11 by Mark_E

But where would these URLs be coming from considering that you won’t find URLs with the .html extension anywhere in a Kirby site.

ok, i guess the .html-routes came from some deeplinks redirecting from the old html-driven site to the new domain. i can’t really explain now, why GSC lists them to the new domain.
i didn’t even know, that route.html works out of the box in kirby, without offering a content-representation-template like we have to do for json or so. is there any reason for that behavior?
i’ll try to make a route which redirects *.html to 404
Thank you!