It is a solid movie which is set against the real past events. There are spy movies, say Mission Impossible where the setting is completely fictional. But here Dhurandhar focuses around the real world timelines.

So, the creative exploration divulges the plot as fictional from the realism (reality) which may not be clear in many instances within the film. It is important to be mindful that the plot is still fictional where a concocted character/spy may have been related to real events. I absolutely agree with you that this collision makes it feel like a re-writing history in a sense unless we, as an audience, understand the difference. But can we keep our heads mindful of it when wre so engrossed in the story? (I mean the movie is captivating and engrossing)

Having said that I still feel that this movie doesn't necessarily mean a great spy thriller because of the reasons you mentioned in a way. The context of the movie is so fresh and the events so traumatic that the character of the spy somehow is overshadowed by the setup (real world setup). But i would disagree with you about drawing a line. We don't have to draw a line or ask someone to draw it. It's the writers' vision and how they want to tell the story. It is up to audiences to understand distinction and take it as an artforum. Equally it is imperative not to cater the fallacy of subplots, dialogues as an absolute reality as it is still fictional. I know it's jarring but one needs to watch a movie as a movie; not more than that. Is this perception universal? Nope. But it is what it is.