WP in subfolder with domain on root

I have a particular case to solve: a hosting plan having different domains, all pointing to the hosting root.
Based on domain visited I directly redirect the traffic to subfolders with a .htaccess on the root folder.

For basic websites it works for WordPress I have some problems: there’s a WP in the root and a WP in a subfolder. When I call “rootdomain.tld/wp-admin/” it replies the root WP, if I call “subfolderdomain.tld/wp-admin/” continues to reply the root WP instead of subfolder WP so I cannot access the backend of subfolder WP.

The root .htaccess is like this

RewriteEngine on
RewriteCond %{HTTP_HOST} ^(www.)?subfolderdomain.tld$ [NC]
RewriteCond %{REQUEST_URI} !^/subfolderdomain/
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^(.*)$ /subfolderdomain/$1 [L]
RewriteCond %{HTTP_HOST} ^(www.)?subfolderdomain.tld$ [NC]
RewriteRule ^(/)?$ subfolderdomain/index.php [L]

# BEGIN WordPress
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /
RewriteRule ^index\.php$ - [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]
</IfModule>
# END WordPress

and the .htaccess in the subfolder is this

# BEGIN WordPress
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /subfolderdomain/
RewriteRule ^index\.php$ - [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /subfolderdomain/index.php [L]
</IfModule>
# END WordPress

The root WP has
site_url: https://www.maindomain.tld
home: https://www.maindomain.tld

The subfolder WP has
site_url: https://www.subfolderdomain.tld/subfolderdomain
home: https://www.subfolderdomain.tld

The root WP works normally (frontend and backend) while the subfolder WP frontend is ok but I cannot access its backend if I try to login via wp-login.php or wp-admin.

Any suggestions?