@Luanti For Debian Trixie users: While waiting for 5.15 to appear in sid, you can package Luanti 5.15 yourself with just a few commands:
Add sid sources to sources.list and then
sudo apt build-dep luanti=5.14.0+dfsg-2
sudo apt install libsdl2-dev devscripts
wget https://github.com/luanti-org/luanti/archive/refs/tags/5.15.0.tar.gz https://deb.debian.org/debian/pool/main/l/luanti/luanti_5.14.0+dfsg-2.debian.tar.xz
tar xf 5.15.0.tar.gz
cd luanti-5.15.0
tar xf ../luanti_5.14.0+dfsg-2.debian.tar.xz
dch --newversion 5.15.0-1 'New upstream version 5.15.0' </dev/null
sed --in-place -r 's/^.*run-unittests.*$|^.*dh_auto_test$//' debian/rules
dpkg-buildpackage -b
dpkg-buildpackage -b
In this case dpkg-buildpackage needs to be run twice to ingnore a warning.