The freeimage and qt@5 formulae used in Gazebo Harmonic and Fortress will soon be disabled in homebrew due to multiple open CVEs in freeimage (see osrf/homebrew-simulation#3298) and the already passed end-of-life for Qt5 in 2025-05. The freeimage formula will be disabled in homebrew-core on 2027-01-10 and qt@5 will be disabled on 2027-05-19. Gazebo Rotary and Jetty have migrated to Qt6 and away from freeimage, and while it may be technically possible to backport these migrations, it is prohibitively costly to do so, especially for the Qt6 migration. Alternatively, it would be possible to maintain our own copy of the freeimage and qt@5 formulae in homebrew-simulation, but this poses a security risk due to the open CVEs in freeimage.
As such, the Gazebo PMC has agreed to drop support for Gazebo Harmonic and Fortress on macOS on 2027-01-10 when the freeimage formula is disabled. Support for ogre1.9 (which requires freeimage) has already been dropped from Rotary and will be dropped from Jetty on 2027-01-10 as well. Gazebo Harmonic and Fortress will continue to be supported on Ubuntu until the end-of-life dates documented at Gazebo Releases — Gazebo jetty documentation