WordPress/wp-includes/blocks/preformatted/block.json

{
	"name": "core/preformatted",
	"category": "text",
	"attributes": {
		"content": {
			"type": "string",
			"source": "html",
			"selector": "pre",
			"default": "",
			"__unstablePreserveWhiteSpace": true
		}
	},
	"supports": {
		"lightBlockWrapper": true
	}
}