Why do non-existent pages return a 200 response?

Question

htaccess

The site has pages like site.ru/some_page.php
but no page like
site.ru/some_page.php/many_different_symbols
and in theory a 404 page should open at this URL, but instead the server gives a 200 response and opens
site.ru/some_page .php/many_different_symbols
(only the site is static and all paths are relative - scripts, styles and pictures are not displayed).
How to get a 404 response on such pages or redirect them to a 404 page.

Answer 1

Adding the AcceptPathInfo Off directive to the .htaccess file did not help in my case.
But the following rules helped, maybe it will come in handy for someone:
To cut off everything that comes after site.ru/some_page.php and get an existing page:
RewriteRule ^(.*php)/.+$ /$1 [R=301,L]
Or to get 404 page:
RewriteRule ^(.*\.php)\/(.*)$ /404.php [R=301,L]

Answer 2

AcceptPathInfo
In .htaccess add
AcceptPathInfo Off