I' have been having a problem with structure

I have been printing some kunai's (from overwatch on my Bambu Lab P1S, The print quality is very good and has been really good but for some reason the faces that are up against the structure/ structure interface turn out super bumpy and i dont know why. i dont know if this is the place to ask. can u at least tell me what this is. i bet then i could research how to solve it