On further investigation this doesn’t occur constantly. Sometimes a black bar appears at the notch of the phone which fixes the incorrect UI placement.
Example:
We are currently A/B testing notch support for 10% of users. Notch support involves rendering the 3D view behind the notch on phones with notches, like the iPhone XS, and also insetting ScreenGui UI by default. This prevents the UI from being covered by the notch unintentionally.
Currently, 90% of users will see the black bar (legacy behavior), if they are selected to not receive notch support. So, that’s why you might see notch support on/off depending on which user is logged in.
If you would like to learn about how ScreenGuis can be customized to render content in the area around the notch, please check out the notch support beta feature post.
Please let me know if you have any questions about notch support!