Hi, let me check this incident under the light of the Technical Collaboration Guideline https://www.mediawiki.org/wiki/Technical_Collaboration_Guideline (draft under review, feedback welcome in the related discussion pages).
https://www.mediawiki.org/wiki/Technical_Collaboration_Guideline/Milestone_c... defines when and where are communications expected.
The change discussed in this thread is a slight variation of the same colors, for accessibility reasons that haven't been contested. This is not a new product or a new feature, and it is not even a major bug. Therefore, not triggering a community announcement & review for this case was correct.
This doesn't forbid anyone to talk about this change, especially when they are one of the contributors (and a volunteer developer) happily sharing the results obtained. Sharing the news with wikitech-ambassadors was correct too.
https://www.mediawiki.org/wiki/Technical_Collaboration_Guideline/Community_d... defines the steps for communities in case of disagreement.
If a change (no matter how small is perceived by their authors) causes problems to a community or an individual, they can file specific blockers explaining the problem. They can do it in the related Phabricator project https://phabricator.wikimedia.org/project/profile/24/ or wiki page https://www.mediawiki.org/wiki/Wikimedia_User_Interface.
So far there haven't been any blockers identified about the change itself, though? If you have any, please report it in the venues where they can be addressed effectively. https://phabricator.wikimedia.org/T152025 seems to be the related task.