Are you saying you moved your UiPath / Robot to AWS or the target system that the Robot is interacting with to AWS?
Only thing that comes to mind, if running Robot in AWS is that AWS only provides Windows Server editions unless you import your own Windows 7/10 image or use AWS Workstations which even then is only Windows 10 Experience on top of Windows 2016. Due to this by default there is increased security settings that you wouldn’t normally find in a non-server version of Windows.
If your selectors of the web based system is changing, is the system it is based on dynamic in the how it renders the source (Are your selectors too specific for the content?), would you have something injecting additional content into the site between the robot and the target.
In any case moving to AWS itself, I can’t think of a reason why the selector would change in any drastic way. If you can provide more details on the differences you are seeing or more specifics about your setup, someone might be able to provide some input.