Subdomain is unexpectedly resolving despite Nginx not being set up to reverse proxy it - nginx

Question

So I have been setting up my home network to host a few websites under a domain (and it's subdomains) using a combination of cloudflare to proxy and provide DDoS protection/HTTPS to the sites, and an Nginx reverse proxy running on my network to allow multiple sites to return from behind the same gateway that the DNS records in cloudflare are pointed at.
For the purposes of this explanation, I will replace my real domain name with [domainNameHere].
The first thing to explain is my DNS setup on cloudflare.
I have 4 CNAME records setup to do the following:
Note that I'm using CNAME records because I do not have a static home IP, therefore I'm using a Dynamic DNS address that resolves to the IP address of my gateway. This same Dynamic DNS address is used in place of an A record as I'm aiming to not need to update A records all the time, and instead just have it resolve via a automatically updating Dynamic DNS record.
[domainNameHere].net - Reverse proxy returns the root site when this domain is requested.
www.[domainNameHere].net - Behaves the same as the above, just there to handle any www requests, the reverse proxy returns the same root site for both wwww and the root domain name.
map.[domainNameHere].net - When this subdomain of [domainNameHere] is called, the reverse proxy instead returns a different site (a map, as you might have guessed).
test.[domainNameHere].net - This is a proxied DNS record setup in cloudflare for future purposes, I do not yet intend for it to actually return a site.
Now, the expected behaviour is that all of these DNS records should currently return a site, expect for test.[domainNameHere].net which shouldn't - I'd expect it to just return a standard ERR_NAME_NOT_RESOLVED like any other DNS record that doesn't actually go anywhere.
Instead though, when test.[domainNameHere].net is used, it returns the root site that [domainNameHere].net and www.[domainNameHere].net resolve to?
Using map, www or the root domain name all return the expected content.
I believe that I have configured something incorrectly in the Nginx settings, below are the two configuration files that are currently in my sites-enabled directory:
server {
listen 80;
listen [::]:80;
root /var/www/html;
index index.nginx-debian.html;
server_name [domainNameHere].net www.[domainNameHere].net;
location / {
try_files $uri $uri/ =404;
}
}
server {
listen 80;
listen [::]:80;
server_name test.[domainNameHere].net;
location / {
proxy_pass http://jake-server:8123;
}
}
Is there anything wrong with my Nginx setup? I thought the behaviour would be that if I haven't setup test.[domainNameHere].net within Nginx, then it wouldn't resolve on the reverse proxy and therefore wouldn't return anything, or would just return the Nginx 404/403 page?
Is it maybe something to do with how the first setup file is setup to point to local files on the proxy, rather than using proxy_pass like is usually done in a reverse proxy?
Or is this not an issue with Nginx, and is an issue with how I've set Cloudflare up?