Hello,
I do not see Subscriptions on your site – https://prnt.sc/y5grdt , so I’ve disabled this plugin.
The mentioned js_composer plugin means WPBakery plugin. You are using an old version of the plugin, so it needs to be updated – https://xstore.helpscoutdocs.com/article/37-plugins-update
If the update of the plugin doesn’t solve the problem with blank pages, provide temporary FTP access, so we can check it more deeply. If you don’t know what the FTP is then you need to contact your hosting provider. Hosting support knows.
Regards