Render Delay randomly slowing Largest Contentful Paint on mobile

[MovingImages]

My website has large variations in Largest Contentful Paint render delays for mobile.

Sometimes there's very little render delay and the Pagespeed performance scores well. Other times there is a very high render delay on the Largest Contentful Paint. I have implemented {preload: true} in the image-banner.liquid to prevent lazy loading on desktop - is there anything like that might help for mobile? The image loads at 19kb on mobile, so its well optimized. What could be causing the intermittent render delay on mobile and what can be done to fix it?

Thanks for your help!