Despite the efforts to make the designs more unique, the

Solution

The term "distinct" means something that is clearly different or unique. The antonym of "distinct" would be something that indicates a lack of clear difference or uniqueness. "Similar" describes things that are alike or not different, which is the opposite of being distinct or unique. Unique and Special are synonyms of "distinct" and thus do not serve as antonyms. Different is close but does not precisely capture the opposite of "distinct" in the context of the question.