New bathtub isn't square
Take it back as defective if it's not to stated specs. Trying to wedge the bottom flush until the floor goes in could crack the finish, if it's just bent out &amp; not actually braced out. If the back wall isn't load bearing, you can plane or cut those studs back, plumbing re-alignment shouldn't be a big deal. Or, add another drywall layer to the foreground wall &amp; make up the remainder with the tile layer. Or. just add tile edging with an ogee type edge.