URLs don't change for 404 and WordPress 404 page does not load

I have designed the 404 page for WordPress however whenever I try typing out an address like https://www.homepage.com/gobblegobble the URL stays the same and the page that is shown is my home page i.e. https://www.homepage.com.

Ideally, for these kind of random links I want the 404.php page to be shown.

My wordpress page is just one page that contains contact links and links to the subdomains (which were made using multi-site). So I ended up removing a lot of ‘unnecessary’ functions related to widgets, search forms etc. that were there on the theme files. I however did not touch 404.php in my theme or any file in the wp-admin and wp-includes. Also when I tried getting a 404 for the individual sites in the multisite network, I was able to get them.

But I’m not getting the 404.php to load for my home page ?? Would it be because of the lack of posts or pages?