Foreseeable harm is any reasonably predictable negative outcome a customer could suffer from a product, service or communication — firms must identify and mitigate it across the product lifecycle, including marketing.
Under Consumer Duty, "foreseeable harm" captures any negative outcome a reasonable firm could anticipate — poor investment fit, excessive cost, misleading communications, inappropriate product for a vulnerable customer. In marketing, this means testing creative for whether it could lead customers to make poor decisions (e.g. implying DB transfer is always beneficial), and logging that assessment in the firm's MI for the Board Duty report.