A few articles covering the bigger pieces:

Xbox transfers Rare and Halo franchise to Activision, proposes closure of Ninja Theory, and confirms another 268 roles cut amid studio restructure

A Halo Director Was Promoted, Then Laid Off By Xbox The Next Day

Xbox continues ‘reset’ with Halo Studios layoffs and Undead Labs divestment

What Studios Were Affected by the Latest Xbox Layoffs?

Undead Labs confirms it is now an “employee-owned studio”

All in all, Insider Gaming lists the following studios as affected directly in the new round of layoffs: Halo Studios, The Coalition, World’s Edge, Treyarch, and Xbox Game Studios (general)