In the meantime, a change is rolling out that definitely isn’t an improvement.
Microsoft announced an upcoming to change to Outlook in the Microsoft 365 admin center.
The same behavior is planned for links in Microsoft Teams “in the future.”
Microsoft told The Verge in a statement that there will be a setting to turn off the behavior.
The email will open in the Outlook app in the Edge sidebar.
Links will open in Microsoft Edge even if it is not the system default online window in Windows."
The change only affects Outlook for Windows, with the Mac, mobile, and web versions currently unaffected.
However, at this rate, Microsoft might update those versions with the same functionality.
Source:Reddit,Neowin,The Verge