tantive

This plugin allows background images to be set for all blocks. 
You can set CSS background-image, background-repeat, background-attachment, background-position-x, background-position-y, and background-size.

Tantive Set Background

Example block scaffolded with Create Block tool.

Presskopp

Presskopp Admin Background allows you to customize the look and feel of your WordPress admin area by adding a background image with optional overlay color and blur effects.
The plugin is lightweight, fast, and applies all changes instantly.
<h3>Key Features</h3>
<ul>
<li>Live background preview (no page reload required)</li>
<li>Media Library integration for image selection</li>
<li>Adjustable overlay opacity</li>
<li>Custom overlay color picker</li>
<li>Optional blur effect</li>
<li>Instant removal and reset</li>
<li>Automatic saving via AJAX</li>
<li>Clean and minimal UI</li>
</ul>
<h3>Usage</h3>
<ol>
<li>Click “Select Image” to choose a background from the Media Library</li>
<li>Adjust overlay opacity and color</li>
<li>Optionally add blur</li>
<li>Changes are applied instantly and saved automatically</li>
</ol>
To remove the background:
<ul>
<li>Click “Remove” to reset all settings</li>
</ul>
<h3>Features</h3>
Live Editing
All changes are applied instantly without reloading the page.
Overlay & Color
Adjust overlay intensity and choose any color to match your admin UI.
Blur Effect
Add a blur layer for improved readability.
Minimal UI
Controls are only visible when a background image is set.
<h3>Support</h3>
For support and feature requests, please use the support forum on WordPress.org.
Copyright (c) Presskopp – https://presskopp.com/

Presskopp Admin Background

Adds a customizable background image to the WordPress admin with live preview, overlay color, and blur.

Tantive Set Background vs Presskopp Admin Background