Most codes say, it's 15" from center to side.
That means left, and right.
Some inspectors let it slide, and some don't.
Some homes have 30" tubs, so the plumber roughs at 45" from the tub wall, leaving 15" from tub to center of toilet.
That works unless someone upgrades the tub to a jetted or cast 32" wide tub. Then you wind up short on the rough-in side dimension.
Sometimes you can ask for a different inspector and hope for the best.
Doesn't allows work though.