I have two views in a map used in field maps. The user sees their view fine(it has been shared to their group), but also the one they should not have access to(not share to them). I dont believe they can see any of the layer features but instead of not loading the feature layer view in the layer list, it shows it with 'layer failed to load' message. I wouldn't imagine this is correct behaviour?
@Kieranmg Did you ever fix the issue? I am having a similar problem.