Website icon not showing in post

Pretty much self-explanatory. My website’s icon is not showing on any of the posts being sent to Discord. Instead of using my icon’s URL, it uses a Discord link that doesn’t work (https://images-ext-2.discordapp.net/external/r2Npcftm1ic5aLDlvUcn0WKmxcJDYtU8zcw6mjyaP1M/https/ecchinyaa.org/wp-content/uploads/en_ico_2017.png) in its place.

I tried fiddling with class-wp-discord-post-formatting.php, to no avail. Here’s what I’ve done to try to make it work:

From:
'icon_url' => get_site_icon_url(),
To:
'icon_url' => get_site_icon_url( $url = 'https://i.imgur.com/C849gaD.png' ),

Of course, it still tried to load directly from my website.

I am using Sucuri’s Web Firewall to protect my website from attacks, by the way. Is it messing up Discord’s image snatching or something?