Comment 1 for bug 2058930

Actually, this seems to be an issue of the source package not being pulled from -proposed, as I can install the binaries just fine in a LXD container:

root@nn:~# dpkg --add-architecture i386
root@nn:~# apt update
[...]
root@nn:~# apt install libvpx9:i386
Reading package lists... Done
Building dependency tree... Done
Reading state information... Done
The following packages were automatically installed and are no longer required:
  libnsl-dev libtirpc-dev
Use 'apt autoremove' to remove them.
The following additional packages will be installed:
  gcc-14-base:i386 libc-bin libc-dev-bin libc-devtools libc6 libc6:i386 libc6-dev libgcc-s1:i386 libidn2-0:i386
  libunistring5:i386 locales
Suggested packages:
  glibc-doc glibc-doc:i386 locales:i386 libnss-nis:i386 libnss-nisplus:i386
The following NEW packages will be installed:
  gcc-14-base:i386 libc6:i386 libgcc-s1:i386 libidn2-0:i386 libunistring5:i386 libvpx9:i386
The following packages will be upgraded:
  libc-bin libc-dev-bin libc-devtools libc6 libc6-dev locales
6 upgraded, 6 newly installed, 0 to remove and 7 not upgraded.
Need to get 15.3 MB of archives.
After this operation, 18.6 MB of additional disk space will be used.
Do you want to continue? [Y/n]
[...]
Get:12 http://archive.ubuntu.com/ubuntu noble-proposed/main i386 libvpx9 i386 1.14.0-1ubuntu1 [1129 kB]

========================================0

root@nn:~# apt-get source libvpx
Reading package lists... Done
NOTICE: 'libvpx' packaging is maintained in the 'Git' version control system at:
https://salsa.debian.org/multimedia-team/libvpx.git
Please use:
git clone https://salsa.debian.org/multimedia-team/libvpx.git
to retrieve the latest (possibly unreleased) updates to the package.
Need to get 4332 kB of source archives.
Get:1 http://archive.ubuntu.com/ubuntu noble/main libvpx 1.13.1-2ubuntu1 (dsc) [2366 B]
Get:2 http://archive.ubuntu.com/ubuntu noble/main libvpx 1.13.1-2ubuntu1 (tar) [4316 kB]
Get:3 http://archive.ubuntu.com/ubuntu noble/main libvpx 1.13.1-2ubuntu1 (diff) [13.6 kB]
Fetched 4332 kB in 1s (8427 kB/s)
dpkg-source: info: extracting libvpx in libvpx-1.13.1
dpkg-source: info: unpacking libvpx_1.13.1.orig.tar.xz
dpkg-source: info: unpacking libvpx_1.13.1-2ubuntu1.debian.tar.xz
dpkg-source: info: using patch list from debian/patches/series
dpkg-source: info: applying 0001-Relax-ABI-check.patch
dpkg-source: info: applying 0002-Do-not-undefine-_FORTIFY_SOURCE.patch