Gsync Pulsar is going to live or die by how well it handles refresh rates that are actually, well, variable. The motion seemed extremely smooth when it was running at 200+ fps on a high-end GPU, but ...
After you are done installing, head over to the Java edition of the game. Now, click on the dropdown menu and check that the list of instances contains Minecraft with Iris Shaders 1.21.11, indicating ...