What is the proposed idea/solution?

...Add either an ellipsis or a small triangle at the corner of a cell that contains additional data that cannot be seen readily, most obviously in the case of a Long Text field when viewing in Grid view at a short row height.

How does is solve the user problems?

...Users might not be aware that important additional content might be present in a cell, especially if row height is short. A simple visual indicator would distinguish between cells where the content is self-evident, versus cells that must be clicked on to see additional content.

How was this validated?

...I don't know.

Who is the target audience?

...All users.