This is more likely a bug with how artifacts are being published when the kernel ABI is bumped during RCs, as the same thing happened during buster until it was released...
Both of these links have OLD artifacts and the installer will not work, thus PXE boots are broken all the same: http://ftp.debian.org/debian/dists/testing/main/installer-amd64/current/images/netboot/debian-installer/amd64/ http://ftp.debian.org/debian/dists/buster/main/installer-amd64/current/images/netboot/debian-installer/amd64/
