That's very fine geometry detail in the balcony. I can imagine that geometry hasn't been reconstructed 100% in your DEM/Mesh? Because then it wouldn't be a texturing problem, as Metashape doesn't have the correct geometry to map onto.
Fixes: can't think of really simple one.
You could create a plane for the front part of the balcony in a 3d app, then orthomoasaic just that geometry in agisoft and then alpha mask that new orthomosaic of just the plane.
However, the wall behind the balcony will still have artifacts. This would require another plane for the wall part with alpha masked balcony images...
What I've done in such cases is to hand model the detailed structures based on the Metashape mesh in a 3d app, import that into Agisoft again and then create the Orthomosaic.
But that's certainly not a "hotfix".