I used the following code in my Shipping confirmation notification email, and it used to return the value a few days ago. However, it suddenly stopped working without any changes to the metafields:
{{order.metafields.custom.something}}
The code {{order.metafields}} returns MetafieldCollectionDrop, but {{order.metafields.custom}} now returns an empty {}.
Additionally, previewing {{order.metafields.custom.something}} in the email templates editor returns a Server error. Inspecting the network tab shows an Internal server error in the API without any specific details.