1.17.2 has been released. While (hopefully) not a visible change, this release adds support for using webp images. This will allow for smaller image file sizes for both mainline and for add-ons and should be working on all platforms, but for now please let us know if it isn’t working - on the main menu you’ll see the background as entirely black if there’s an issue.

For additional details, as usual see https://r.wesnoth.org/t55532