Duotone: Caching breaks duotones set through theme.json

[scruffian]

Description

When a duotone filter is set through theme.json, the SVGs are output to the footer using a side effect of gutenberg_render_duotone_filter_preset. This happens the first time that Global Styles are generated. However, once this has happened the output value is cached. Once the cache is primed, Global Styles aren't generated in the code anymore, which means the side effect of gutenberg_render_duotone_filter_preset doesn't happen and the SVGs aren't output. This means that all images with a duotone applied via theme.json disappear.

Step-by-step reproduction instructions

1. Ensure that your environment doesn't have any of these consts set:

   gutenberg/lib/compat/wordpress-5.9/get-global-styles-and-settings.php

   Line 79 in 3e84b56

   $can_use_cached = (

2. Apply a duotone filter to a theme via the theme.json file:

			"core/image": {
				"filter": {
					"duotone": "var(--wp--preset--duotone--default-filter)"
				}
			}

	"settings": {
		"color": {
			"duotone": [
                {
                    "colors": [ "#000", "#B9FB9C" ],
                    "slug": "default-filter",
                    "name": "Default filter"
                }

3. On the first load this works fine, on subsequent loads the images break

Screenshots, screen recording, code snippet

No response

Environment info

No response

Please confirm that you have searched existing issues in the repo.

Yes

Please confirm that you have tested with all plugins deactivated except Gutenberg.

Yes

[ajlende]

Interestingly, when I set $can_use_cached = true, sometimes none of the theme.json styles load. These screenshots are using the skatepark theme.

EDIT: It seems to happen when I switch from false to true for a minute or so. It looks like the the set_transient call that happens assumes that there is something in the cache already even when it isn't. This can probably be disregarded.