The prayer is valid.
However she should try her best to keep it leveled as much as possible

Is the prayer of a woman who bows for her hands to reach her knees but her back is not levelled/flat in ruku’ -is this valid?Before I thought our spine/back had to be straightened flat but heard that some scholars say the prayer of a woman who bows a bit is valid. I would like to find out so I know whether I should advise other sisters on this matter or not.