Why is it using いらなくなった instead of いらなかった here?

Question

This is the sentence I am trying to understand:
Context: They are talking about recycling

これはいらなくなった服でお母さんが作ったんだ

I understand the meaning, which would roughly be: My mother made this with clothes that were not needed. My question is, why is it using that verb conjugation: いらない+なる=いらなくなった (to become not needed).

Am I missing some nuance in the translation? Why is the sentence written in this way and would this be incorrect or unnatural?:

これはいらなかった服でお母さんが作ったんだ

みなさんありがとう！

Answer 1

My nuance is as follows:

いらなくなった服：　used clothes　[使]{つか}い[古]{ふる}し

いらなかった服 ：　leftover clothes　[余]{あま}り[物]{もの}

いらない服　　　：　unneeded clothes　[不要品]{ふようひん}

Answer 2

いらなくなった has nuance that "I needed the clothes before but it became not needed now."

I think いらなかった don't have the nuance like "I needed the clothes before.".