Can you get into legal trouble for using a decal that isn't free to use?

For example, if you were to make a script that got that assetID of a group icon, then added that to a game, could you get into legal trouble for displaying that group’s icon in your game (assuming it isn’t your own group)? Likewise, could you get in legal trouble, even if the developer gave consent to use it?

You probably won’t get into trouble if you asked for permission,

Wouldn’t that be considered advertisement for that group though?

TL:DR Depends on the icon and authors of that icon. If it isn’t that serious or was unintentional then no, no legal trouble. If you are really unsure about it then seek/ask a real professional.

It technically would be considered advertisement for that group, so I’m not sure why developers would do that, but supposedly it is an issue.

If it is an issue then it’s probably best to listen to the author(s) and find what the issue is.