Why would a female just not want to compliment another female?

For context, I'm at university, there's this girl that will compliment everyone but me when the chance presents itself. I'm not saying I'm desperate but there are days when I genuinely put in effort an di look good and she won't compliments me but will find a way to call to tell tiwhr girls around me they look pretty. We're kinda friends with each other and we have good talks, so I find this weird. I showed her a Pic of me when I was younger, and then she was like "you were so cute, what happened" and then laughed - tbh that's the closest I've come to a compliment from her. She will however compliment my friends all the time.

Why would a female just not want to compliment another female?
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