Milankumar Sanandia

This plugin will WP Disable Block Editor & enable the Classic Editor and original Edit Post screen (TinyMCE, meta boxes, etc all).
<ul>
<li> Disable Block Editor on page and Enabled Old Editor.</li>
<li>Admin Option for Enabled/Disable Gutenberg Block Editor.</li>
</ul>

WP Disable Block Editor

This plugin will WP Disable Block Editor & enable the Classic Editor and original Edit Post screen (TinyMCE, meta boxes, etc all).

Sumit Singh

Classic Widgets with Block-based Widgets allows you to use both widgets screens at the same time. 
Sometimes, you need to use the classic widget screen for some of the widgets without permanently disabling the block-based widgets. With this plugin, you can access the Classic Widgets screen in <code>Appearance > Classic Widgets</code> and the block-based screen at the usual place in <code>Appearance > Widgets</code>.
NOTE:- 
This plugin uses WordPress filters to create a new classic widget screen. That means it will work as long as WordPress supports the Classic Widgets screen.
<h4>Links</h4>
<ul>
<li><a href="https://github.com/5um17/classic-widgets-with-block-based-widgets" rel="nofollow ugc">GitHub repository</a></li>
</ul>

Classic Widgets with Block-based Widgets

Restore the classic widgets screen as a new menu item without replacing new block-based widgets.

WP Disable Block Editor vs Classic Widgets with Block-based Widgets