How to redirect from a subdomain to the main site?

Question

Apache HTTP Server

Good afternoon!
Faced such a problem, there is a main site and a subdomain. You need to redirect from the subdomain to the main site only if this is not an authorization page, and not the main page of the subdomain.
Tried to do so

RewriteCond %{HTTP_HOST} sub\.site\.ru [NC]
RewriteCond %{REQUEST_URI} !^/user(.*)$ [NC]
RewriteCond %{REQUEST_URI} !$ [NC]
RewriteRule ^(.*)$ https://site.ru/$1 [L,R=301]

When you need to catch subfolders, everything is fine, but how to make it "not the root of a subdomain"?
Tried !^/$ doesn't work either. In the variant as described above, the redirect does not occur at all.

Answer 1

Added the rewrite output to the Apache log and in the end it turned out like this

RewriteCond %{HTTP_HOST} ^sub\.site\.ru [NC]
RewriteCond %{REQUEST_URI} !^/user(.*)$ [NC]
RewriteCond %{REQUEST_URI} !^/$
RewriteCond %{REQUEST_URI} !^/index.php$
RewriteRule ^(.*)$ https://site.ru/$1 [L,R=301]

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