Do Safari Extensions provide support for .svg toolbar icons?

Do Safari Extensions provide support for .svg icons in the toolbar?

According to MDN, extensions should support .svg icons for "default_icon" within the "browser_action" field of the extension manifest. Testing this on Safari 15 (both macOS and iOS) I get the following error in the preferences pane:

Failed to load default_icon image for the browser_action or page_action manifest entry.

My manifest looks like:

"browser_action": {
   "default_popup": "popup.html",
   "default_icon": "images/toolbar-icon.svg"
}

and I am using a basic SVG exported from SF Symbols 2.

Thanks! 😁