I’ve been testing two .htaccess file in root folder and there was the same result.
(website installed in example.com/my_subdir and running using example.com)

The first one

RewriteEngine on
RewriteCond %{HTTP_HOST} ^example.com$ [NC,OR]
RewriteCond %{HTTP_HOST} ^www.example.com$
RewriteCond %{REQUEST_URI} !my_subdir/
RewriteRule (.*) /my_subdir/$1 [L]

The other is

<IfModule mod_rewrite.c>
RewriteEngine on
RewriteCond %{HTTP_HOST} ^(www.)?example.com$
RewriteCond %{REQUEST_URI} !^/my_subdir/
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^(.*)$ /my_subdir/$1
RewriteCond %{HTTP_HOST} ^(www.)?example.com$
RewriteRule ^(/)?$ my_subdir/index.php [L] 
</IfModule>

Can you please tell me what is the differences and what config is better?