Seams in your 3D model’s UV maps in Substance typically stem from UV unwrapping issues (like overlapping islands or unmerged vertices) or mismatched texture baking settings between your 3D software and Substance.
If UV islands aren’t properly separated or edges aren’t welded in your 3D tool, Substance can’t align textures smoothly across seams. Baking normals/occlusion maps with different smoothing groups or resolution than Substance expects also creates gaps.
To fix this, ensure UVs are non-overlapping and edges are merged in your 3D software, then match baking parameters (resolution, anti-aliasing) before importing to Substance.