backports-5.3-rc4-1 was released. This is based on Linux 5.3-rc4.
https://cdn.kernel.org/pub/linux/kernel/projects/backports/stable/v5.3-rc4/backports-5.3-rc4-1.tar.xz

backports-5.2.8-1 was released. This is based on Linux 5.2.8.
https://cdn.kernel.org/pub/linux/kernel/projects/backports/stable/v5.2.8/backports-5.2.8-1.tar.xz

backports-4.19.66-1 was released. This is based on Linux 4.19.66.
https://cdn.kernel.org/pub/linux/kernel/projects/backports/stable/v4.19.66/backports-4.19.66-1.tar.xz

There is now a updated wiki page with the releases:
https://backports.wiki.kernel.org/index.php/Releases

The source code can be found here:
https://git.kernel.org/cgit/linux/kernel/git/backports/backports.git/

Hauke