Spurious URls

This is the same question as your previous ones, and comes with the same response – it is not necessary to redirect spurious 404s. You will slow your site down. It does not help.

You can use https://regex101.com to test regular expressions. Redirection uses exactly the same regular expressions, and if it matches there then it will match on your site. A cache may affect this.

You can find more information here: https://redirection.me/support/problems/url-not-redirecting/

You can’t see or know what I am currently facing?

I agree that 404’s don’t really hurt SEO, but there’s definitely a lot I can miss out if I don’t fix them?

I have backlinks pointing to pages on my website that return a 404 and trying to fix them with your plugin and 301 redirects have are broken URLs to the relevant locations.

But you could have answered with a solution to the problem posed, right?

You said spurious, not backlinks.

I answered your problem with a link to https://redirection.me/support/problems/url-not-redirecting/ where you can find details about URLs that don’t redirect.

Specifically:

Server Configuration
If your URL is a file then your web server may be configured to handle it directly rather than pass the request through to PHP and WordPress.

This means that Redirection could be unable to redirect it. For example, a URL that ends with .pdf, .html, .doc, .png, .jpg, .php, .mp3, .zip, .aspx etc.

Solutions:

Delete the file from your server. If the file exists then it may prevent any redirects.
Save the redirect to Apache .htaccess.