FLUX LoRA Fine-Tuning: Border Outpainting and Pixel-Level Misalignment Issues in Image Editing

Why does the flux.2-klein-base-9b model, when fine-tuned via LoRA on pixel-aligned pre- and post-edited image pairs with prompts for an image editing task, exhibit slight border expansion (outpainting), a failure to preserve pixel-level structural consistency, and minor detail distortions during inference?