Webflow staging site appears in Google Search results, not my connected custom domain

Client’s domain: https://www.jacksonwink.com/
Webflow staging site: https://jackson-wink-mma-academy.webflow.io/

When I enter my Client’s business name in Google Search, Jackson Wink, the search results show the Webflow staging site, and not the custom domain.

How can I correct this?

Here is my site Read-Only: [LINK]1
(how to share your site Read-Only link)

Ooh, gnarly problem.

The standard solution would be to setup a Google search console property for the https://jackson-wink-mma-academy.webflow.io site and then use the removals tool once you’ve verified ownership. However verifying ownership might be difficult since you do not own the webflow.io domain or have access to the DNS.

So I’ve given this some more thought and written up 3 solutions here.
Looking at Google search, this problem is pretty common- there are well over a million webflow.io search results…