DACPAC Deployment Rebuilding All Indexes
The most likely reason this is happening is because there are different options / settings on the indexes in the model (the dacpac file) and the target (your actual database).  The deployment, by default, will rebuild the index with the new options to get the target to match the model.

There are two deployment options you can enable to avoid this.  I would try them one at a time to see which one is causing the rebuild:

/p: IgnoreIndexOptions=True
/p: IgnoreLockHintsOnIndexes=True


There are two more options that ignore index-related things (IgnoreFillFactor and IgnoreIndexPadding).  These are enabled by default, but you might want to check and make sure your publish process isn't explicitly setting them to False.