While the OP seeks a synonym for “does not matter,” by the time I arrived on the scene @Catija had already submitted a perfectly apt response, after which, if the adjective “irrelevant” wasn’t acceptable, all that was required to find one that was, was a quick googling of the adjective and, voila tout!---unimportant, immaterial, inconsequential, insignificant, meaningless, trivial ... More @Wikipedia
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