There have been 3 releases of fractgen since it was added to ports. I've just patched the 2.1.7 release for Qt 5.15.2, but it'd be nice to just catch up with upstream releases. Note that there is a PR (against 2.1.10) specifically for Qt 5.15.2 compatibility, so there's more to do than just update to that release.
^Triage: Reporter is committer, assign accordingly.
A commit references this bug: Author: adridg Date: Wed Jan 6 00:38:45 UTC 2021 New revision: 560461 URL: https://svnweb.freebsd.org/changeset/ports/560461 Log: Update graphics/fractgen to latest upstream release The release is a month or two old by now. Some Qt 5.15.2 patches have landed in the release, but not all of them. New translations require additional dependencies and patching in the right directory to search (PREFIX/share). There are no useful release notes for this release. PR: 251335 Changes: head/graphics/fractgen/Makefile head/graphics/fractgen/distinfo head/graphics/fractgen/files/patch-git-48cf904f47d9eb3819e6e5f6c19feaae0a3bf901.diff head/graphics/fractgen/files/patch-src_CMakeLists.txt head/graphics/fractgen/files/patch-src_colorschemeinterface.cc head/graphics/fractgen/files/patch-src_fractalalgorithminterface.cc head/graphics/fractgen/files/patch-src_fractalgenerator.cc head/graphics/fractgen/files/patch-src_fractgen.cc head/graphics/fractgen/files/patch-src_imagedisplay.cc head/graphics/fractgen/files/patch-src_imagedisplay.h head/graphics/fractgen/pkg-plist
Committed an own update and reported the FreeBSD patches upstream.