I'd assume that would probably be more that "CoPilot all-the-things" took priority over "leave Outlook in maintenance-only mode".
Even the "round all the corners" changes seemed mostly "free" from component library upgrades from changes in other Office and Windows apps and components shared with "New Outlook" (on the one side: people keep assuming New Outlook is a bloated web app, especially because it has a lot of UI consistency with Outlook.com now, but there's a lot of evidence it is more complicated that just a web app; on the other side: a lot of those painting problems especially during resizing relate to Old Outlook has been partly "a web app" for a long time; hybrids apps are hybrid).
Even the "round all the corners" changes seemed mostly "free" from component library upgrades from changes in other Office and Windows apps and components shared with "New Outlook" (on the one side: people keep assuming New Outlook is a bloated web app, especially because it has a lot of UI consistency with Outlook.com now, but there's a lot of evidence it is more complicated that just a web app; on the other side: a lot of those painting problems especially during resizing relate to Old Outlook has been partly "a web app" for a long time; hybrids apps are hybrid).