The plugin simply uses in-built hooks (use_widgets_block_editor and gutenberg_use_widgets_block_editor) to disable the block editor from managing widgets and restore the ‘classic’ widget appearance settings. There are no apparent issues with this basic code.
There may be related issues to be aware of, for example https://tipsnfreeware.com/how-to-disable-the-widget-block-editor-in-wordpress-5-8/ warns that “If you have started using the new block-based widgets system, you will lose all of your widget blocks upon activating the plugin.”. This has not been confirmed by the reviewer, so it is advised to test this functionality before use on production sites.
Be aware of there may be limited ongoing support for this as it provides legacy functionality, although the description states: “It will be supported and maintained until at least 2022, or as long as is necessary”.
Reason for the 'Use with caution' result
The plugin has been given this recommendation at the tester's discretion:
The plugin is rated as safe as it simply provides a convenient way to hook into core WordPress functionality to toggle the block editor managing widgets. It is rated ‘use with caution’ to highlight that switching these widget settings may affect widgets already populated. There could also be conflicts if themes or plugins use the same hooks. Potential issues such as these should be assessed and tested on non-production sites. There is also likely to be limited support in the long-term. However, overall, the plugin is assessed as safe and provides a convenient functionality.