Thank you for raising this concern.
I have posted my thoughts on Dev's trauma will copy it here.
Impact of childhood trauma is very difficult to understand, it impacts ones adulthood, relationships, behaviour, and overall cognitive functioning. Adversities faced in childhood cause disruption of the child's stress hormones - leading to chronic hyper-arousal and ongoing sensitivity to stress. Children, who are threatened with adversities, adapt a stress response in form of fight, flight and freeze, in an extremely prolonged and repetitive fashion.
Dixsit family lived their lives in a survival mode. Dev fought with his circumstances, against all odds he turned around his life for his family and mother. During his journey from rags to riches, he formed a toxic relationship with his mother, which dominated his life.
Sona's presence in his life brought considerable changes in Dev's life. But time and again when he is reminded of his trauma, his mind reminded of his maladaptive coping mechanisms. For instance,Dev was reminded of his childhood when he found out about Ish job, thus, he showed his agitation and frustration. Likewise, 'bus incident' and 'fire incident' has triggered him and he is responding and coping in ways he has been, his signs are similar to 'hyper arousal'.
I could be wrong. Just expressing my POV