Add a checkbox to node group inputs to force inputs to be single values and not accept varying fields. While this could also be done more automatically, and it could be argued that requiring the flexibility is helpful for users who want to use attributes, there are cases where the field inferencing doesn't work, or the "use attribute" option is just unhelpful. People use workarounds with primitive nodes to get the same behavior anyway. Pull Request: https://projects.blender.org/blender/blender/pulls/112745