When using getMatchedRules() from declarativeNetRequest
(https://developer.chrome.com/docs/extensions/reference/declarativeNetRequest/#method-getMatchedRules), the item that is returned contains a "url" field instead of the MatchedRules object which should contain a ruleId and rulesetId:
https://developer.chrome.com/docs/extensions/reference/declarativeNetRequest/#type-MatchedRule

This is an example of what is returned:
rulesMatchedInfo: [
	{
		request: {url: "https://example.com"}
		tabId: 2
		timeStamp: 1686247475669.134
	}
]

As shown above, it only has the "url", not the rule.

The changelog states that for Safari 16.4 getMatchedRules() "fixed result of getMatchedRules() to match other browsers" (https://webkit.org/blog/13966/webkit-features-in-safari-16-4/), however this still doesn't seem to return the same thing that other browsers do.

getMatchedRules() does not give the rule that was matched. It doesn't have the rule ID that was used (e.g. 1, 5, etc), and it does not have the ruleset ID (i.e. the id of the static rules file if it was from the static rules, or if it was a session rule: "_session", or if it was from the dynamic rules: "_dynamic").