They have been marked as deprecated for a while
application.secret since https://www.playframework.com/documentation/2.4.x/Migration24#Configuration-changes and play.crypto.secret since https://www.playframework.com/documentation/2.6.x/Migration26#Other-Configuration-changes
A pull request would be very welcomed here.
A PR will be arriving ;)
Hi guys, I created a PR on removing the play.crypto.secret and application.secret on https://github.com/playframework/playframework/pull/9061