ECS Role Changes?

Hi,

I have recently deployed a new app and have discovered that there may have been a change with regards to how the security roles work.

I have previously used the global rack InstancesRole in order to apply permissions on resources, but it appears that the credentials provider using a different mechanism to AssumeRole or there has been a change.

Through trial and error I discovered that the ECS Service ServiceRole is now being assumed. Is this behaviour expected and/or have there been any recent changes?