Post Install Redirect for apps, has something changed?

Question

In my appDescriptor I have set up a postInstallRedirect like so:

modules: {
postInstallRedirect: {
key: 'redirect',
        url: `https://bitbucket.org/{user_username}/workspace/settings/addon/admin/${appKey}/repository-settings?post-install=true`
    }

This used to work perfectly but recently something has gone wrong and now after installing I see the page as follows:

Can someone help explain how this could have happened? 
I see no change logged in this area from Bitbucket?

Thanks in advance,
Emma

George Mihailoff · Answer

Maybe something to do with the rollout of the new UI.

https://community.atlassian.com/t5/Bitbucket-questions/How-can-I-enable-the-new-bitbucket-interface/qaq-p/583276