In release 2308 for both Office 2021 and Microsoft 365 an Add-Ins group with one button has been added to the right end of the Home Tab in Office applications.
This seems to duplicate the first Add-Ins button on the Developer Tab but has a different icon.


It cannot be modified using the Customize the Ribbon dialog and I know of no other way to get rid of it.
Someone at Microsoft thinks that the Store Add-Ins are not getting enough attention from users. To me, this is a waste of valuable screen real estate.
It is the subject of at least two posts on the Microsoft Answers Word forum.

• How to remove Add-ins from Home Ribbon in Word? - Microsoft Community
• Add-Ins group/button on the Home tab. Added with version 2308. Unable - Microsoft Community

I posted a discussion about it in the Microsoft Answers Excel forum and I've posted negative feedback about this. Feel free to comment and vote.
Excel: I do not want or need the Add-Ins group/button on the Home Tab. Please at least let me remove it. · Community


I posted a similar note in the Word forum.