As any Extension on Magento Marketplace, JaJuMa WebP Optimized Images is developed to work with Magento Default. While trying as far as feasible to avoid conflicts with, or breaking other custom functions, we cannot guarantee so for every imaginable customization out there.
Specifically in case you have other customizations regarding how images are delivered to your customers (such as lazyloading, image swap on hover, images served from CDN…), the extension might still work fine. But it is also possible there might be conflicts preventing the extension from working as expected.
It totally depends on how your custom implementation is designed to work.
However, besides supporting 3 different conversion tools we also added some configuration options trying to have the extension work in as many scenarios as possible.
Please check the manual chapter 4.3 for Advanced Configuration options.