JUX Before After is a simple Joomla extension that beautifully shows the visual changes between two images (Before image and after image) on the same screen.
Demo: https://joomlaux.com/jux-extensions/image/jux-before-after.html
Comparimager is a lightweight and simple WordPress plugin for Elementor to compare images in a slider.
Demo: https://codecanyon.net/item/comparimager-before-and-after-image-compare-for-elementor/39031303