Confusion between mobile version and site desktop: caching problem?


Hallo!!! Good morning to the community. I apologize for my English not perfect. I have the free version of Cloudflare but I’m having problems with the theme (Newspaper) that no longer distinguishes between the desktop version and the mobile version of the site. Has anyone had a similar problem? Can this be caused by the wrong Cloudflare settings? I claim that the site runs on Siteground (which has its own caching system) and I also installed the WP Rocket plugin from which I disabled the cache for mobile terminals (even WP Rocket is perfectly compatible with Cloudflare). Can you give me a tip?
Thanks a lot.