Currently, there's logic that determines all options have been selected when the length of selectedOptions is equal to the length of options (combo_box.js#L300). This is fine when the combo box is consumed as in the first example in the docs, and custom options are pushed to the array of available options.

But if the consumer doesn't change the list of available options then at some point the user may add enough custom options that the check referenced above erroneously evaluates to true. When this occurs, the user will incorrectly see the "You've selected all available options" message.