WPE + Wp-Rocket + webP

with Optimus, mobile lazy needs to be disabled (iOS bugs) ā‡’ https://docs.wp-rocket.me/article/139-disable-lazyload-on-mobile

Alternative use Imagify...

From: WP Rocket

In this scenario you are using server-side caching from WP Engine and using WebP on your site. When using a different page caching method other than WP Rocket, it is only possible to use WebP by using the Picture Element method from Imagify. Using webp (Optimus) with WP-Engine won't work correctly.