It always build with qt4, no matter the qt5 useflag is set or not. This applies to both of the two versions (15.11.0 and 15.11.0-r1). I read the ebuild and looks like the author forgot to add the qt4/5 branching code. Reproducible: Always Steps to Reproduce: 1. Set use flag "qt5". 2. Build media-video/smtube Actual Results: 3. It actually builds with qt4. Expected Results: with qt5.
Commenting to acknowledge the issue. I will be looking to fix this tomorrow. Thanks for reporting and assigning. Apologies for the error.
Bug fixed by commit 2de0dc577a8cdc8d304ab3ce24d2584134e3f5fa in git. Tested building with USE="qt5" and USE="-qt5", both variations built and function as expected on ~amd64. Marking as resolved; if any corner case pops up, please re-open. Thanks again for reporting!