Going to https://apps.twitter.com/app/<app_id>/permissions and clicking the link from
https://apps.twitter.com/app/<app_id>/permissions
Read more about our Application Permission Model.
opens up https://dev.twitter.com/docs/application-permission-model.
It should be https://developer.twitter.com/en/docs/basics/authentication/overview/application-permission-model instead.
Thanks, I have an open ticket for our team to add a redirect here. This was a result of our recent site migration. We apologise for the confusion caused here.