Simulate Backend user is displayed for normal users in user settings
When you are logged in in the Backend as a normal user you do not have the right to simulate a Backend user.
Sill the tab "Admin functions" is visible and inside this tab a string "Simulate backend user" is shown. But no dropdown after it.
The tab and the field should not be visible for normal users. A workaround is using User TSConfig:
setup.fields.simulate.disabled = 1