Reproduction with expectation

Given I am using Firefox
And my editor is set to Atto
And I am on my Profile Editing page
And I set the HTML content of the editor to:

<img src="https://moodle.org/theme/moodleorg/pix/moodle_logo_TM.svg" alt="It's the Moodle" width="204" height="61" class="img-fluid atto_image_button_text-bottom">

When I click on the image
And I preess the link button
And I set the link to https://moodle.org/
And I se the title to My link title
And I save changes
Then the image should have an anchor around it with an href value of https://moodle.org/
And the image anchor should have a title of My link title

Actual

The image anchor is set to My link title
The image href is not set

h3 Diagnosis

The behaviour has changed somewhere between Firefox 105.0.3 and Firefox 109.0.1

If you enter the original content into Atto, and select it, then using developer console run:

document.execCommand('createLink', null, 'https://moodle.org/');

Then the content is replaced with:

<a _moz_dirty=""><img src="https://moodle.org/theme/moodleorg/pix/moodle_logo_TM.svg" alt="It's the Moodle" width="204" height="61" class="img-fluid atto_image_button_text-bottom"></a>

Afetr much fiddling and trying to work out what's going on I discovered that this is linked to the use of the atto_image_button_text-button class, and specifically the fact that this class has a property set of:

display: inline-block;

https://bugzilla.mozilla.org/show_bug.cgi?id=1906559