Chrome does not have release notes. The blog post only mentions CVE fixes and points you to Git logs for the rest of the work. Only a tiny number of new Chrome features (out of the thousands of changes and bug fixes done in every release) get further marketing treatment, and they are obviously going to focus on those directly relevant for users over a new video codec. Just because they didn't call out the change anywhere doesn't mean they are being secretive about it, as the title wants to imply.
The top of the Chromium blog [1] currently says "Find the release notes for Chrome Beta 107 here." and they point to [2].
Which is definitly not marketing treatment -- it's deep in the weeds of changes for CSS, JavaScript, HTML, and so forth.
It's obviously not including every change made, but it does seem like it's intending to be fairly comprehensive in terms of new relevant changes for developers.
