Unable to use catalog image in discord webhook

When sending an embed to a webhook to Discord from Studio, the specified thumbnail URL does not load in the embed. I’ve tried the link (shown below), as well as the ContentId format. What would I use to be able to fetch the asset image link and use it in the embed?

["embeds"] = {
		["title"] = "Test Embed",
		["color"] = tonumber(0x2b2d31),
		["thumbnail"] = {
			["url"] = "https://www.roblox.com/Thumbs/Asset.ashx?Width=256&Height=256&AssetID=1029025"

Result: image

Discord webhooks are blocked by Roblox.

They are, but you can still send them using a proxy. My issue is that I am unable to put an image/thumbnail of a Roblox asset on the embed.

I believe you need to retrieve user thumbnails in the Players service.