Indeed, it looks like a slight manufacturing oversight; the pressed metal fingers do too good of a job of retaining the plastic bungs
Several options though given that it looks like they aren't part of the subsequent retaining mechanism for the stay-bar
Probably the simplest and least alarming for you would be to get a wood saw out and cut the bung down the channel along these two lines:
View attachment 336571
The middle bit of big will drop out and the sides can be pried, twisted, levered, broken or even just cut off at the curved end and left in place
Or, you can use a drill in the indentation clear away the aluminium and form a hole that removes the retaining finger
Or you can look to bend the aluminium up a bit moving the metal finger away from the bung
changes to the metal of the ladder in this location will have no effect on its overall structural integrity because the point where the weight of the ladder and user bears onto the stay bar is above these points