This release contains a couple of improvements and some general updated.

Additional CSS

We have restored the ability to add additional CSS in the customiser and the Styles of the Site editor.
You can again edit the styles of your site. Read more on the new CSS page.

New Plugin: Contact Form Block

We have added a new contact form with Google reCatcha v3 to Block themes.
The Jetpack contact forms did not work in the block editor. You can now use this plugin in Block Theme sites. Read more about the plugin & other form options on the Contact Form page.

Various plugins & theme have been updated.