When I start the OAuth process for Search Keywords import, why do I get redirected to my homepage?

This can happen when you enter your website URL in the Authorized redirect URIs rather than your Matomo URL (when setting up Google oAuth config client). This needs to be set to your Matomo URL including the query string for example:

https://matomo.my-website.com/index.php?module=SearchEngineKeywordsPerformance&action=processAuthCode

Refer to the guide on setting up the search keywords import.