The spin Nernst effect of magnons (quanta of spin wave excitations) was theoretically proposed in 2016 in collinear antiferromagnetic materials, but its experimental confirmation remains elusive. In 2017, around the same time when its electronic counterpart was experimentally observed, the spin Nernst effect of magnons was first claimed in transition metal trichalcogenide MnPS 3. However, the experiment involved ambiguities that cannot convincingly verify the spin Nernst effect of magnons, awaiting further experimental studies. With a more accurate description accounting for real device geometry, it was believed that optical detection should be more reliable than electronic detection. At present, optical detection of the spin Nernst effect of magnons has not been reported.