GdSb_0.46Te_1.48, a nonsymmorphic Dirac semimetal with Dirac nodes at the Fermi level, has a rich magnetic phase diagram with one of the phases predicted to be an antiferromagnetic skyrmion state. In the current work, we investigate GdSb_0.71Te_1.22 through bulk magnetization measurements, single-crystal, and powder synchrotron X-ray diffraction, as well as single-crystal hot-neutron diffraction. We resolve a weak orthorhombic distortion with respect to the tetragonal structure and charge density wave (CDW) satellites due to incommensurate modulations of the crystal structure. At 2 K the magnetic structure is modulated with two propagation vectors, k_I = (0.45 0 0.45) and k_II = (0.4 0 0), with all their arms visible. While k_I persists up to the transition to the paramagnetic state at T_N = 11.9 K, k_II disappears above an intermediate magnetic transition at T₁ = 5 K. Whereas magnetic field applied along the c-axis has only a weak effect on the intensity of antiferromagnetic reflections, it is effective in inducing an additional ferromagnetic component on Gd atoms. We refine possible magnetic structures of GdSb_0.71Te_1.22 and discuss the possibility of hosting magnetic textures with non-trivial 3D+ 2 topologies in the GdSb_1−xTe_1+x series.