Michael Sumner

<blockquote>
Does one thing: disables the Widget Block Editor feature.
</blockquote>
Activate this plugin to disable the Widget Block Editor functionality (added in WP version 5.8). To re-enable the widget block editor at any time, simply deactivate the plugin.
Features
<ul>
<li>Simple to use – activate and done.</li>
<li>No permanent modifications are performed.</li>
<li>There are no configuration options to worry about.</li>
<li>Easy peasy.</li>
</ul>
Why is this useful?
WordPress 5.8 was launched on July 20, 2021, and contained some enhancements to the WordPress block editor. Among those features was an introduction to WordPress’s new Widget Block Editor.
Now, why would you want to deactivate this function in the first place? You may have script conflicts that prevent you from using the widgets due to the block editor and conflicts with other plugins.
Privacy
This plugin does not collect or store any information about the user. It does not use cookies or link to any third-party websites. Thus, this plugin has no effect on the user’s privacy.

Disable Widget Block Editor

Activate this plugin to disable the Widget Block Editor feature that was added in WP v5.8.

Nhat Huynh Van

<blockquote>
It’s hard to change if you love something!
</blockquote>
I’ve been using the original/classic editor for over 10 years now and the experience has always been 100% smooth and the original Visual Editor was awesome. 
I like to keep that to myself and I’m sure there are some people like me who like the classic, easy to use and simple thing.
This plugin disables the new Gutenberg Editor (Block Editor) and replaces it with the Classic Editor. 
The Disable Gutenberg plugin restores the classic (original) WordPress editor and the “Edit Post” screen.
Features
<ul>
<li>Classic Editor</li>
<li>Disable Block Widgets and restore Classic Widgets</li>
<li>Enable/disable frontend Gutenberg stylesheet</li>
</ul>
<blockquote>
Works same as Classic Editor plugin, but lightweight, simple and super fast
</blockquote>
Easy to Use
<ul>
<li>Super simple</li>
<li>Clean, secure code</li>
<li>Built with the WordPress API</li>
<li>Lightweight, fast and flexible</li>
<li>Works great with other WordPress plugins</li>
<li>Focused on flexibility, performance, and security</li>
</ul>

Relive Classic

Plugin Relive Classic is help you use editor, widgets in classic style and disable Gutenberg.

Disable Widget Block Editor vs Relive Classic