Your plugin works wonderfully — fast, reliable, and very well designed. I just wanted to share a little tip that might help with your future updates.
There’s another plugin that manages to convert images to WebP without changing the media ID: WebP Image Converter & Replacer – Image Optimisation, No Duplicates, Save Disk Space – https://ww.wp.xz.cn/plugins/webp-image-converter-replacer/.
Maybe taking a look at how they handle the conversion process could provide some inspiration for adding this functionality to your already excellent plugin. I’m sure many users would love having both the current performance and the media ID preserved.
Keep up the great work!