Adding a suffix confuses autocomplete?

Hey community!

So this is something that's bugged me for years.  I go to add a suffix to an identifier, say during a casual refactoring or perhaps like in this case I am choosing a subclass of the identifier I originally used.  I start typing, and it shows me the autocomplete for it and I think to myself: great!  Except then I hit tab or enter to complete it, and it does this:

Did I misconfigure something a long time ago and forget that I did it, or is this the normal behavior?  I feel like it should be smart enough to see that a suffix autocompletion is happening.

Thanks!