The instant Leia sees Luke, she suddenly commences struggling against the Imperials who have her in custody. She breaks away just long enough to warn him at the top of her lungs that it’s a trap.
She doesn’t scream for help, even though she and Chewie and Threepio are in Imperial fucking custody and are probably about to be shipped to the goddamn Emperor for Sith-style interrogation/torture/gloating.
She doesn’t know Lando’s changed his mind and is orchestrating their escape.
She can’t be sure they won’t blast her in the heart for trying to warn Luke.
Leia is a goddamned selfless hero and people need to not fucking forget it.