Fixing a Color System That Only Signals State Through Hue

A fintech app's transaction list uses color as follows: completed transactions have a light green row background, pending transactions have a light yellow row background, and failed transactions have a light red row background — no icons, no text labels, no other visual difference between the three states. A support ticket comes in from a user who says they "can't tell which transactions failed" and describes difficulty distinguishing red and green in general.

1. Diagnose exactly what's wrong with this design, in terms of the color-as-signal principle from this subject.
2. Propose a fix that keeps the color coding (useful for most users) but resolves the reported problem. Be specific about what you'd add to each of the three states.
3. Beyond this specific list, what does this bug suggest about how the product's broader color system should be structured going forward, and why?