Brevo/SendInBlue unsubscribe webhook

I have been looking at the code and can see a webhook has been implemented for when a user unsubscribes within Brevo but I can't seem to get the webhook working.

I can see in RouteProvider.cs I think it should be

https://storedomain.com/Plugins/Sendinblue/UnsubscribeWebHook

base on the code:

            endpointRouteBuilder.MapControllerRoute(SendinblueDefaults.UnsubscribeContactRoute, "Plugins/Sendinblue/UnsubscribeWebHook",
                new { controller = "Sendinblue", action = "UnsubscribeWebHook" });

but when I put this into Brevo as a webhook I get a "400 Bad request" response. The nopCommerce log doesn't have and additional information.

Can someone confirm the webhook URL is correct? Has anyone got this to work before?

What happens if you just navigate to that URL in the browser?

I get a 405 error, I assume that it will be expecting a POST and not a GET

Yes, true. (But I think it means that at least that the route is valid)
Do you have Postman?

I have, but I don't know what data is expected

Thanks for the info. We'll fix this soon, here is a work item to follow.
Btw, what version of the plugin?

I am on nopCommerce 4.5.2 and plugin version 3.38