Of course trauma profoundly affects self-esteem. It rips the rug out from under the self. It changes the way our brains work. It changes the way the world looks. The lessons that traumatic experiences teach us related to our own sense of agency are not ambiguous.
Self-esteem often returns rapidly during EMDR reprocessing. It appears to increase in the session at the same rate that distress decreases. It’s astonishing to see. If you have a genuine interest in cognitive therapy, I have found nothing that more adaptively changes self-talk and resolves cognitive distortions than reprocessing the experiences that taught us that we are bad and that this world is serpent. Clients do this through noticing. They do this without confrontation, without homework, without worksheets, and without the presence of a therapist sitting in a position to judge which thoughts are adaptive or maladaptive. They do this almost entirely on their own, which is a great exercise in self-esteem. They do something that is difficult and astonishing. And, they do this almost entirely inside each 55 minute session.
EMDR is a faster and deeper means to accomplish a lot of goals at once. Deep healing accomplishes many goals at once.