It was producers that chose who got parts on the songs, they would all go in the studio and record parts and the production chose the structure of the songs. And they were catered to a younger audience at the time, but once Camila left the group they went to a more grown up direction and to make the group dynamic work they want everyone to have an equal opportunity to shine.
it's a pretty known fact that the company themselves wanted Camilla to be the lead and center of the group, which is why she's given the most lines. when she left, the group had more freedom to shine more and gain more control of their songs
basically their management favored Camilla before she left. after she left they got to showcase their talent equally. like Dinah (The tallest blonde member) said.. their producer said her voice was too soulful for their records. if she wants to have lines in their song, she has to babied up her voice to match with pop singing style.. fun fact Dinah, Normani and Lauren are more to RnB singers
because camila's voice is so different from the rest of them, i think producers didnt know how to blend her in well so they tended to just give her the main choruses or parts where she didnt need to blend. also the label for sure was pushing camila to be the center. when she went solo she signed with the same label they were on
