Images with transparent backgrounds have black backgrounds on firefox (including opengraph previews)

[jms301]

Describe the bug

When posting an image with a transparent background or a link to a page which has an opengraph image with a transparent background on firefox linux the background is black.

To Reproduce

Steps to reproduce the behavior:

1. Attempt to make a post using firefox on linux linking to a page such as: https://en.wikipedia.org/wiki/Gartner_hype_cycle

Expected behavior

The open graph image has a background colour matching the linked page. This seems to work fine on:
https://www.opengraph.xyz/url/https%3A%2F%2Fen.wikipedia.org%2Fwiki%2FGartner_hype_cycle
For example it should look like this:

It looks like this:

Details

• Platform: Linux
• Platform version: Mint 20.3
• App version: Firefox