The attention mask in the T5 part of flux and SD3 utilizes the text-side attention mask to make the model focus more on text embeddings during image generation, thereby enhancing semantic alignment with the text.
https://github.com/leeguandong/ComfyUI_FluxAttentionMask
git clone https://github.com/leeguandong/ComfyUI_FluxAttentionMask
comfy node install ComfyUI_FluxAttentionMask