How do Aurena image controls work?

In the Aurena page designer, I see an option to set a control as type “image”. How does this work?

Since BLOBs aren’t supported as custom fields, I tried filling in this field with some SVG text to see if my web browser would like that.

<?xml version="1.0" encoding="utf-8"?>
<svg xmlns="http://www.w3.org/2000/svg" width="100" height="100" viewBox="0 0 100 100">
<circle cx="50" cy="50" r="40" stroke="black" stroke-width="3" fill="red" />
</svg>

Aurena puts in a placeholder image no matter what I seem to set this field to…

How is this supposed to work?

Is this improved in IFS Cloud?