We can do that when it’s actually released; blogspam tries to publish on the expected release date before the actual release so it can scoop up the clicks. Release notes should be posted here later: https://www.mozilla.org/firefox/120.0/releasenotes/
So you’re saying: don’t release the GTK 3 port until colour spaces are also complete? Why not give people what’s ready, and then when colour spaces are ready, cut another release? No need to make people wait who don’t need colour spaces.
(Additionally, it’s easier to verify that bugs reported before the release of colour spaces are more likely to be related to the GTK3 port.)