When adding a text overlay within an image operation chain ... a TextStyleTransformer is required.
Current existing class info.magnolia.imaging.operations.text.TextStyleTransformer extends info.magnolia.content2bean.impl.Content2BeanTransformerImpl (which is deprecated).
We should deprecate this class and provide a TextStyleTransformer which extends info.magnolia.jcr.node2bean.impl.Node2BeanTransformerImpl.
With existing classes it seems impossible to add a text layer.

Also ensure the new component is registered in the module. Right now, if you want to use TextStyleTransformer, it must be registered in a module descriptor:

<components>
  <id>main</id>
  <component>
    <type>info.magnolia.imaging.operations.text.TextStyleTransformer</type>
    <implementation>info.magnolia.imaging.operations.text.TextStyleTransformer</implementation>
  </component>
</components>