odd neighbour stares at my window (?)

hello everyone i’m 19m and i’ve moved 1 year ago now in this apartment.

there’s a girl whose bedroom’s window is right in front of my bedroom’s window, the girl is supposedly around my age, and i spot her very very often to check behind the curtain or stand on her balcony supposedly staring at my window / me when i’m not looking at her, if she sees i’m seeing her she immediately steps back and go away or just pretends she’s minding her business.

that’s all she does, she’s not doing (too) creepy thing, just stares and tries to not be noticed.

what can i do about this? oh and i do not know her i have no idea who she is or what’s her name or anything of the sort, i’ve never even seen her around.

any advice?