rwmj did mention about an unintentional embargo break, so I wonder whether this is GitHub issue is actually it.
I'm the author of such PR. My purpose was to trim down the size of the initram files by removing unneeded dependencies.
I couldn't imagine that liblzma had a backdoor.
But many others followed, like libselinux: https://github.com/systemd/systemd/pull/19997
libqrencode: https://github.com/systemd/systemd/pull/16145
p11kit: https://github.com/systemd/systemd/pull/25771
tpm2-util: https://github.com/systemd/systemd/pull/28333
libiptc: https://github.com/systemd/systemd/pull/29836
libkmod: https://github.com/systemd/systemd/pull/31131
Exactly during the development of the libkmod PR, someone noted that libxz could be lazily loaded too: https://github.com/systemd/systemd/pull/31131#issuecomment-1...
And so I proposed myself to to the job, nothing less, nothing more.
If you look at the code of the other PRs, you see that they are very very similar, there are also macros to easy this task, like DLSYM_FUNCTION()
To be more precise, the first public comment asking to dlopenify lzma was dated 30 Jan by Daan: https://github.com/systemd/systemd/pull/31131#issuecomment-1...
The day after, it was reiterated by Lennart: https://github.com/systemd/systemd/pull/31131#issuecomment-1...
But if you look in the systemd repo there is a TODO file with a section of libraries which needs to be lazy loaded. liblzma was added in this list in June 2020 (https://github.com/systemd/systemd/commit/cdfd853744ee934869...) by Lennart, and removed by me just after that my PR was merged.