Problem with quotes... Let's try a heredoc instead.

.gitea/workflows/build.yaml

@@ -504,21 +504,24 @@ jobs:
 
           curl -H "Content-Type: application/json" \
               -X POST \
-              -d '{
+              $DISCORD_WEBHOOK_URL \
+              -d @- <<EOF
+{
+  "username": "BuildBot",
+  "avatar_url": "https://i.imgur.com/28JJJec.png",
   "content": "✨ **New Build Available!** ✨ (THIS IS A TEST)",
   "embeds": [
     {
-                        "title": "'"$EMBED_TITLE"'",
+      "title": "$EMBED_TITLE",
-                        "description": "'"$EMBED_DESCRIPTION"'\n\n**Build Name:**\n'"$BUILD_NAME"'\n\n🚀 **Primary Download Link:**\n'"$DOWNLOAD_LINK"'\n\n🔗 **Torrent Link:**\n'"$TORRENT_LINK"'\n\n🧲 **Torrent Magnet Link:**\n'"$MAGNET_LINK"'\n\n**Mirrors:**\n\n🚧 In order to conserve bandwidth, please consider using the *above* methods to download the release. If you have issues using those methods, you\'re free to download using any of the following HTTP mirrors.\n\n🚧 While the links *below* are not secret, **do not advertise them**. The primary MEGA link or torrent should be used to advertise any downloads.\n\n'"$DOWNLOAD_LINK"'",
+      "description": "$EMBED_DESCRIPTION\n\n**Build Name:**\n$BUILD_NAME\n\n🚀 **Primary Download Link:**\n$DOWNLOAD_LINK\n\n🔗 **Torrent Link:**\n$TORRENT_LINK\n\n🧲 **Torrent Magnet Link:**\n$MAGNET_LINK\n\n**Mirrors:**\n\n🚧 In order to conserve bandwidth, please consider using the *above* methods to download the release. If you have issues using those methods, you're free to download using any of the following HTTP mirrors.\n\n🚧 While the links *below* are not secret, **do not advertise them**. The primary MEGA link or torrent should be used to advertise any downloads.\n\n$DOWNLOAD_LINK",
-                        "url": "'"$DOWNLOAD_LINK"'",
+      "url": "$DOWNLOAD_LINK",
       "color": $EMBED_COLOR,
       "footer": {
-                          "text": "'"$FOOTER_MESSAGE"'"
+        "text": "$FOOTER_MESSAGE"
       },
-                        "timestamp": "'"$TIMESTAMP"'"
+      "timestamp": "$TIMESTAMP"
     }
-                    ],
+  ]
-                    "flags": 4100
+}
-                  }' \
+EOF
-              $DISCORD_WEBHOOK_URL
         shell: bash