HELP! One Multisite url not working when removing www.

Hi all,

Can somebody help me with the following issue.
I have a multisite with 8 sites on subfolders.
example: https://www.mainsite.com/multi1, https://www.site.com/multi2, etc etc.

All of the sites including main, work when removing https://www., typing : https://www.mainsite.com/multisite1

But one of them, doesn’t work and redirects me to the main site when removing www.
So for example, when I type the URL: https://www.mainsite.com/multisite7/ it doesn’t work and redirects me to https://www.mainsite.com/

But on all the other multisites, it does work.
when I type the URL: https://www.mainsite.com/multisite2/ it goes to the multisite it supposed to..

How can I solve this?

I already tried adding this to my public www htacces file

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

and also tried

RewriteCond %{HTTP_HOST} !^domain_to_exclude_from_www_redirect.com [NC]
RewriteCond %{HTTP_HOST} !^www\.
RewriteRule ^(.*)$ https://www.%{HTTP_HOST}/$1 [R=301,L]

someone please help.