@atarifrosch You mean from the Resynthesizer plug-in? It has never been a part of core GIMP. Though we have always recommended it to people. It's a great plug-in!

I'm pretty sure it will soon be ported to GIMP 3.0 (in fact, I know there is already a branch on their repo for GIMP 3 API), especially as it is maintained by one of our core developers these days.