Session Start Warrning and FORCE_SSL_ADMIN notices only if user not logged in

I am having a problem with some pages on our website. It is throwing the following errors:

Warning: session_start(): Cannot start session when headers already sent in /home/quaffoqn/public_html/wp-content/plugins/templatesnext-toolkit/inc/woo-compare-wishlist/includes/compare/compare.php on line 20

Notice: Constant FORCE_SSL_ADMIN already defined in /home/quaffoqn/public_html/wp-config.php on line 83

Notice: woocommerce_recently_viewed cookie cannot be set - headers already sent by /home/quaffoqn/public_html/wp-content/plugins/woocommerce-menu-extension/woocommerce-menu-extension.php on line 20 in /home/quaffoqn/public_html/wp-content/plugins/woocommerce/includes/wc-core-functions.php on line 835

This error only happens if:
1. The website is accessed via https rather than http
2. The website is accessed if a user is not logged in, if they are there is no error.

I have also checked wp-config.php it used to have the force_ssl_admin in it but I have removed it. I have deleted the wp-config.php to force no cache, and then reloaded the backup, I have renamed it still an issue. The template-next is standard. I have tried disabling the plugin and still get an issue. Any guidance to try and solve this would help

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