Bootstrap v5 has reached beta status. That means no more new features or breaking changes in the future releases of the V5 branch. We're testing it out on this website.
The most confusing thing when you inspect responsive images is the fact that the browser takes into account the DPR (Device Pixel Ratio) in order to download the most appropriate image size. Find out here how to serve your visitors responsive images.
Bootstrap 5 utilizes both theme-color("primary") and $primary color defintions. This article details how to override and extend the theme-colors using Sass.