Is the server response on the site correct?

Question

htaccess

There is such a site.
Is it normal that the site responds with 200OK to all non-existent pages? Shouldn't the site return a 404 Not Found response?
For SEO, is it better to leave it as it is or make the server response be 404 Not Found?

Answer 1

Best of all 404 and html page at the same time.
If there was something at this address before, but now it is permanently deleted: HTTP 410 Gone