How long were the bullet holes present in the glass from the non-inverted perspective?

Question

In the first half of Tenet, there is a scene where The Protagonist and Neil break into Freeport and find a glass wall with bullet holes (could only find a good photo with Christopher Nolan in it):

In the next scene, we find out that these bullet holes were caused by an inverted armed man entering the room (exiting the room from their perspective) and reverse-shooting the glass, which removes the bullet holes from the future-facing perspective. This all makes sense, but raises a question: how long were the bullet holes there in the first place? Were they in place as soon as the glass was installed, possibly years ago? Or even back when the glass was manufactured?

Answer 1

Questions like this do touch the nerve of the film's logical consistency.

In our normal, non-inverted timeflow, when you shoot a wall/glass, the resulting hole remains in it indefinitely and only gets worse with time. It will eventually get buried/destroyed after the building gets demolished. The hole will not magically self-heal / disappear.

In Tenet's inverted timeflow the laws of physics are deemed to be all the same. It's just the entropy/time that flows in the opposite direction. So, there should be no reasons to presume that the behaviour of a bullet hole shot by an inverted round would be any different in its timeflow. Like with a normal bullet hole, it should be worsening with its time going forwards (ours backwards), not self-healing.

What that means is that, logically, the hole got formed it its worst/oldest state in the glass right when it was solidifying from liquid silica at the glass factory. Yes it was essentially a factory-made flaw/defect which, for whatever reasons, was ignored by the factory's QA, glass supply chain, the builders and the Freeport vault staff all the way along. Think they all were on Tenet's payroll or whatever.

Like Barbara said to the Protagonist: "Don't try to understand it. Feel it". I don't think Christopher Nolan intended to make it completely logically consistent and making sense. It's just supposed to be a "wow" to impress the majority of viewers who will simply say "Ingenious! Let's go see it again, maybe we'll understand some more".

Answer 2

The in-universe explanation is that traces of all interactions between inverted and regular objects were always present in our universe. What has happened - happened.

So as soon as the glass was made it was already cracked, although the cracks were microscopic. Then they would grow larger and larger until they form a complete bullet hole at some time prior to the event.

All this is clearly explained during the inverted trip to Oslo.

1. When the inverted Protagonist, Neil and Cat board the container, it is specifically shown that the Protagonist's right biceps is bothering him.
2. During the trip, judging by Protagonist's emotions, it starts bothering him even more.
3. When they arrive at Oslo airport, it is bothering him so much that Protagonist rolls up the sleeve and looks at his arm. We can see that there is some kind of a bruise on his right biceps.
4. Just a few seconds prior to leaving the container, Neil sees blood dripping from Protagonist's right arm, but they have no time to investigate.
5. From that moment, it is about 20 minutes give or take until he gets stabbed exactly in his right biceps.