Then again, Alder Lake is so 2021, which in the IT world is like bread from August. Joke of course, coming from someone writing this with an i5-4570.
Seriously though, stories like these show why it is good to keep on top of knowing which BIOS/UEFI version one has and how to update it, especially if an network-admin, etc. E.g. less than a year ago there was an update fixing issues with some Intel CPUs, and around the same time AMD also had a patch fixing an issue for some CPUs (in this case a drivers patch).
Which isn't to say that the leak surely means that a security flaw has been exposed. For all we know, it may be just some instructions like one gets when assembling some furniture piece. But if a flaw gets exposed, it is likely to get addressed, and up to users though to implement the fix, in particular on a level which doesn't come with automatic updates.
Having source code doesn't lead to hackers suddenly knowing how to get inside, they could already figure that out by just bashing against a binary. What this does is let custom ROM folks have an idea on how to build custom roms for this platform, which enables features that Intel and MB makers wouldn't want enabled.