The Marigold Mask in Mortal Shell 2 is a very useful piece of special equipment. To obtain it, you should play through the Prologue and avoid skipping it directly. Although you can still acquire it later, doing so is much more troublesome. To get the Marigold Mask, look for marigolds during the Prologue.
How to Obtain the Marigold Mask in Mortal Shell 2