Images have no alt text

A screen reader can't see an image: it reads the alt attribute instead. When there is no alt at all it falls back on whatever it can find, which is usually the file name: "I M G underscore 4 0 3 2 dot J P G". The same text is what shows when the image fails to load, and what a search engine takes the image to be of.

An empty alt="" is not a mistake. It is how you say "this is decoration, skip it", and it is right for flourishes, spacers and an icon that sits beside a word saying the same thing. What is flagged here is the attribute being absent, which says nothing either way.

Source: WCAG 2.2, 1.1.1 Non-text Content (Level A); W3C's alt decision tree.

Say what the image shows, as you would to someone on the phone, and leave out "image of":

<img src="/cakes/three-tier.jpg" alt="Three-tier wedding cake with sugar peonies">

For decoration, keep the attribute and leave it empty:

<img src="/flourish.svg" alt="">

In WordPress it is the Alternative Text box in the media library.