Interestingly, both Starlight Glimmer and Harley Quinn are characters who were once villains but later redeemed and joined the heroes. I feel that pre-redemption Harley would likely dislike Starlight both before and after Starlight's redemption, since Harley loves being chaotic and wouldn't like being subjected to order by someone above her, but with Harley as of the end of Mayhem in the Multiverse where she is still chaotic but has joined the heroes, there's a chance she could get on with Starlight. I'm reminded of the episode #TheWarriorAndTheJester prior to the movie where Wonder Woman is very annoyed with Harley's antics, unfortunately we never get to see how Diana and Harley might get on after the events of Mayhem in the Multiverse.