The latest stable Debian release is codenamed "buster" and comes at the end of a 25-month development period. Debian 10 will be supported for the next five years and comes with many updated packages, support for ten architectures — including older 32-bit PCs, as well as a wide range of desktop environments: Cinnamon, GNOME, KDE Plasma, LXDE, LXQt, MATE, and Xfce.
https://www.notebookcheck.net/Debian-10-buster-now-available-for-download.427149.0.html
'php 6.3' ? i would guess that should be 7.3.
It wouldn't be the first time for a new Linux release to come with some older package included. Debian 10 also comes with Firefox 60.7, and we all know that version 68 is just around the corner. Most likely they are adding packages that get long-term support from their makers. However, you are absolutely right about PHP. It was entirely my mistake. Thank you very much for pointing it out!