With the WordPress 5.5 beta release around the corner, all PHP changes since Gutenberg v7.5 have to be merged with Core. Since we already want to merge Gutenberg 8.4 into core (updating the JS packages), this needs to be done as soon as possible, before 2020-06-24.

• Update Packages GB 8.5 (JS): Update WordPress Packages wordpress-develop#347
• Update Packages GB 8.5 (JS)

• Block Patterns: https://core.trac.wordpress.org/ticket/50445
• Block API
  • WP_Block and WP_Block_List: https://core.trac.wordpress.org/ticket/49926
  • Block Type endpoint: REST API: Expose blocks registered on the server wordpress-develop#317
• Image Editing endpoint
• Block Directory: REST API: Introduce Plugins and Block Directory endpoint wordpress-develop#359
• Compat
  • Update default block categories: https://core.trac.wordpress.org/ticket/50278 Together with package update.
  • Register block from block.json metadata file: https://core.trac.wordpress.org/ticket/50263
  • Remove default "layout" block attribute from WP_Block_Type::get_attributes: https://core.trac.wordpress.org/ticket/50257

It looks like the following files have changed.

git diff release/7.5...master --name-only -- 'lib/' | sed 's/.*/[&](https:\/\/github.com\/WordPress\/gutenberg\/commits\/master\/&)/'

I collapsed some directories that contain one feature.

? = Undecided
x = Not for this release
A = Assigned

A lib/block-directory.php (Block Directory) @tellyworth
A lib/blocks.php (Block API) @gziolo @epiqueras
A lib/class-wp-block-list.php (Block API) @gziolo @epiqueras
A lib/class-wp-block-pattern-categories-registry.php (Block Patterns) @youknowriad
A lib/class-wp-block-patterns-registry.php (Block Patterns) @youknowriad
A lib/class-wp-block.php (Block API) @gziolo @epiqueras
A lib/class-wp-rest-block-directory-controller.php (Block Directory) @tellyworth @TimothyBJacobs
A lib/class-wp-rest-block-types-controller.php (Block API) @spacedmonkey @TimothyBJacobs
x lib/class-wp-rest-customizer-nonces.php (Navigation Screen)
A lib/class-wp-rest-image-editor-controller.php (Image editing) @ajlende @TimothyBJacobs @azaozz @ellatrix
x lib/class-wp-rest-menu-items-controller.php (Navigation Screen)
x lib/class-wp-rest-menu-locations-controller.php (Navigation Screen)
x lib/class-wp-rest-menus-controller.php (Navigation Screen)
A lib/class-wp-rest-plugins-controller.php (Block Directory) @tellyworth @TimothyBJacobs
x lib/class-wp-rest-widget-forms.php (Widget Screen)
lib/client-assets.php
A lib/compat.php @gziolo
x lib/demo-block-template-parts/header.html (FSE)
x lib/demo-block-templates/ (FSE)
x lib/edit-site-export.php (FSE)
x lib/edit-site-page.php (FSE)
x lib/editor-features.php (Global Styles)
x lib/experimental-default-theme.json (FSE)
x lib/experiments-page.php (Internal)
x lib/global-styles.php (Global Styles)
x lib/load.php (Internal)
x lib/navigation-page.php (Navigation Screen)
A lib/patterns/ (Block Patterns) @youknowriad
lib/rest-api.php
x lib/template-loader.php (FSE)
x lib/template-parts.php (FSE)
x lib/templates.php (FSE)
x lib/utils.php (Internal)
x lib/widgets.php (Widget Screen)

To know what changed in specific files, I use git diff release/7.5...master -- lib/compat.php for example.