When we update the layers etc within a web map, these layers may not have the same permissions as the web map that the layers are contained within. When you try to save these web maps AGOL presents you with a warning like this one:
The warning is good, but it could be much better by adding two more columns, one showing the feature layers current permissions, and another showing what permissions it needs to be visible to all map users.
The map creator can then make a much more informed decision about whether or not they want to modify the original feature layer permissions or not.
Basically I find the warning window very confusing and without the extra details I am requesting, I am usually guessing whether I should click update or cancel!