In the just released WordPress 6.9 there is a new feature that makes it possible for users to hide blocks. It’s a convenient feature to use when you want to hide a block for a period of time instead of deleting it completely.
In this post we’ll show you how you can detect such block visibility changes in the Simple History activity log.
WordPress 6.9 now includes a built-in feature to hide blocks, making it easy to tuck content away without deleting it. You can now hide blocks: select a block, click the ellipsis, and choose “Hide”. Hidden blocks are visually removed from the editor, and fully omitted from the published markup. Scripts and styles for hidden blocks are also omitted from the rendered page by default (see WordPress 6.9 Frontend Performance Field Guide for more details).
https://make.wordpress.org/core/2025/12/01/ability-to-hide-blocks/
Technically the visibility of a block is controlled by a new block property called blockVisibility. Settings this value to true simple prevents the output for happening and all the PHP code for controlling the output (preventing the content of the block from being outputted on the frontend) is controlled with just a few lines of code in the file block-visibility.php.
When a block is set to be hidden you can easily spot this in the post content diff. Just look for the text blockVisibilityand then if the new value is false the block is hidden.
When the block is made visible again the blockVisibilityattribute is removed, so just look for that.
