Here are 2 workflows that contain the node Masks Subtract:

1.

Size: 24920 bytes

URL: https://github.com/maxixa/colab/blob/465c403b8a8bbf690cbd4ce9c19377ed2eaddf7c/comfy-workflows/json/controlnet-alpha-inpaint-lora-prompt-auto-mask-3.json

2.

Size: 353715 bytes

URL: https://github.com/abyz22/image_control/blob/7a3a5403db3d9217e8fecb3826ce37facd4ff2ef/imgs/sample.json