Responses
I think the reason for the sudden outfit change was just to don't get readers confused with some possible "lover's matching clothes" or anything like that. At first I thought this whole thing about a couple showing up in matching clothes was just a Korean thing, but maybe it's a Chinese thing, too…?
Its a minor thing but I bet the author found that he liked having contrasting color between LiHuan and YuYang when composing this chapter. It ended last week with them both in white hoodies.