The issue here is actually that your prompt is too detailed. Dall-E works best when generating images off of prompts up to 50 words and ignores anything after word 128. In the case of your above prompt, the widescreen request (assuming that is still the issue you are trying to work out) comes after the 128th word. You can create a long-context prompt in a txt document, and then ask GPT to make it more concise for you, and that should help.
Example:
“A brown rabbit with textured fur sits beside a basket of vibrant Easter eggs, clutching one gently, in a scene that fills the entire frame with no perimeter. Its eyes gleam, reflecting warm light. The background, with creamy whites, pale yellows, and spring flowers, extends to the very edges of the widescreen frame, leaving no border. The impressionistic style with bold strokes enhances the bright spring morning ambiance, fully occupying the widescreen format without any margins.”
There is some good discussion on the Dall-E AMA you can check out here:
Also, I have a GPT you can use for iteration on art if you want to check it out. It provides meta data details to help you iterate on an image, has more educational language in its instructions than the current Dall-E implementation and also is able to work around some of the existing constraints (multiple images, adjusting your prompt etc). that may make things easier for you.