Theme's editor palette colours not previewing in editor

[laurelfulford]

Describe the bug
As of 7.9, it looks like the editor colours provided by the theme don't preview in the editor; they used to be added inline on the element, but now are not. Custom colours seem to work as expected.

I can reproduce this in Twenty Nineteen; Twenty Twenty includes its custom colours in the editor styles so it still works there; I thought it may be a change to move away from inline colours, but I couldn't find a related ticket; please close if that is the case, though!

To reproduce
Steps to reproduce the behavior:

1. Start with a test site running Twenty Nineteen, and Gutenberg 7.9 or 7.9.1.
2. Add a paragraph block to a page or post.
3. Give the paragraph block a colour and a background colour, using the theme's colour palette.

Expected behavior
That the colours would be applied.

Screenshots
Note: it looks like the text is disappearing in Twenty Nineteen -- it's actually the white text colour coming from the theme when the background is set to a darker colour. It is applying the .has-background class, and the related padding, but no background colour.

Editor version (please complete the following information):

• WordPress version: 5.4
• Does the website has Gutenberg plugin installed, or is it using the block editor that comes by default? Gutenberg plugin
• If the Gutenberg plugin is installed, which version is it? 7.9 and 7.9.1.

Desktop (please complete the following information):

• OS: Mac OS
• Browser Firefox
• Version 75

[skorasaurus]

I'm not able to reproduce this on 11.2 Gutenberg.

If you're still able to reproduce this in the newest version of Gutenberg, please reopen.