https://www.theregister.co.uk/2020/01/22/office_365_bing/

Users who install or update Office 365 Pro Plus, part of the Office 365 subscription for larger businesses, will find their browser search engine automatically set to Bing, according to Microsoft documentation.

"Starting with Version 2002 of Office 365 ProPlus, an extension for Microsoft Search in Bing will be installed that makes Bing the default search engine for the Google Chrome web browser,” says the admin guide.