Should date formatting work in extension web template?

I’m trying to use the Web Template under the Extensions settings menu on macOS.

I was hoping I could use something like:

---
date: [[date|%Y-%m-%d]]
title: [[title]]
source: [[url]]
---

to save something like

---
date: 2021-12-07
title: The Best Title
source: https://example.com
---

However when running the share extension from Safari I’m getting the following output (date template tag doesn’t render anything with or without the | and strftime syntax):

---
date: 
title: The Best Title
source: https://example.com
---

Thanks in advance for any help on this!