The piece in question is Olivia's denim skirt ... something Pops isn't on board with, even offering up some suggestions as to how to make it more PC. She posted a clip of her dad's comments Wednesday, showing other family members jumping in to support the fashion statement.

She put a poll online after the discussion, asking if the fit was inappropriate ... her fans made it clear -- no way!!!

You'll recall, Olivia's outfit choices got her in trouble back in January ... an American Airlines worker told her she needed to put a blouse on over her outfit in order to board her flight.

After Olivia was forced to wear BF Christian McCaffrey's hoodie, her sister Aurora pointed out another passenger who was wearing a similar top, but wasn't asked to cover up.