> By using Workers to do this, it resulted in Readme's Cloudflare account receiving requests from our domain with "googlebot" useragent, but from an IP that wasn't verified as a googlebot IP address (I assume the Worker was requesting the Readme site using the Googlebot user agent but with whatever IP address is used when using CF Workers).

Was this definitely the cause? It's somewhat surprising to hear that requests would be rejected if the user agent doesn't match a set of hard coded IP addresses.

Were you able to resolve this in the end? If not and the cause is what you suspect then perhaps changing the user agent in your worker might be a workaround.