Following Justice League, reshoots became a dirty word for superhero movies; despite every movie having them and they’re a normal part of the filmmaking process. Months ago when the Birds of Prey reshoots were revealed, some online claimed they were redoing the entire movie…when in reality nothing like that happened.
Prior to the reshoots the movie was broken up into chapters like a Tarantino movie. The reshoots made the non-linear scatterbrained style that you saw in the first act of the finished film.
But beyond that, they really didn’t change much. The police station scene was greatly expanded and the action, specifically in the amusement park finale, was punched up a lot.
There’s not some secret cut lying around that’s completely different and depending on who you talk to the reshoots improved the movie greatly, although there may be some who would’ve preferred the chapters structure it originally had.