If you have a page or post that was created using the popular Beaver Builder plugin, you can convert that content to the Block Editor (Gutenberg) in WordPress:
- From the WordPress admin panel, choose Pages > All Pages.
- Hover your mouse over the page you want to convert, to reveal a few choices. The dot following the Beaver Builder link will be green, showing that the layout is currently in Beaver Builder.
- Click either Edit or Block Editor, depending on your editor settings in Settings > Writing.
This will result in opening your Beaver Builder layout in the Block Editor (Gutenberg), and converting the layout into a single Classic block. From there, you can select the More options menu, then Convert to Blocks.
I would not recommend disabling the Beaver Builder plugin until you’ve converted all your content to Gutenberg.
Hope this helps, but for more details, be sure to visit the official documentation on Beaver Builder’s own website: https://kb.wpbeaverbuilder.com/article/588-convert-content-between-wordpress-5-and-beaver-builder