You can take a look at:
https://www.cloudflare.com/en-gb/learning/performance/how-to-make-a-site-mobile-friendly/
You can also try to turn on Cloudflare Mirage · Cloudflare Speed docs. Cloudflare Mirage reduces bandwidth used by images in mobile browsers. It can accelerate loading of image-heavy websites on very slow mobile connections and HTTP/1.