Disable duotone svg output in theme.json

I noticed that my theme was outputting a dozen or so extra <svg>s in the footer of my site’s HTML. So, I dug in to find out what and where the WordPress Block Editor (aka Gutenberg) was doing. Ideally, I wanted to remove this superfluous output. Unnecessary markup = unnecessary extra markup for browser engine’s to render.

First, I found out where this was happening in Gutenberg: lib/block-supports/duotone.php

I found that if you add the following to your theme.json then the <svg> will no longer be output.

	"version": 1,
	"settings": {
		"color": {
			"duotone": null
Screenshot of Gutenberg toolbar after duotone support is removed
No more duotone options after adding “duotone”: null to theme.json

Of course, you will no longer have duotone options in the toolbar for blocks that support it, but that is fine by me.