Install v3.0.1 of this module on a fresh Drupal 10.3.6 site with composer and enable it. Follow the provided help:
Enable the text format filter Display responsive images or Display image styles and select the images styles/responsive styles that you want to be available to the user.
Create new content. In the editor, click on the image icon in the toolbar. A popup will open where the user can upload an image then assign an image style or responsive style by selecting style from a dropdown menu.
On step 1, as soon as you visit any of the default text formats' edit pages, you get 3 warnings (last one is repeated twice):
Those go away after you actually enable the image style filter, but this represents a problem for the text filters that won't enable them (eg. Plain text), that will always display the error to the Admin / Site builder.
Active
3.0
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