One thing that just occurred to me: Maybe the headset was not correctly positioned in front of your eyes or the interpupillary distance was not set up correctly

One thing that just occurred to me: Maybe the headset was not correctly positioned in front of your eyes or the interpupillary distance was not set up correctly. If these are not perfect (but good enough) you can still get depth perception and immersion but the fatigue will increase a lot. Also, the headset must basically be “glued to your face”, so it does not sway when moving the head. A high-performance PC is also very important, every FPS drop will induce nausea. I can play HL Alyx for hours on end but still get dizzy when I become dehydrated or hungry. I only have first-hand experience with an HTC Vive (1st gen) though, which uses room-scale laser tracking. I also only ever played room-scale.