Por que Arya está visivelmente assustada na biblioteca do Game of Thrones S8E3?

No Por dentro do episódio David and Dan (showrunners) say the reason she is more scared here is because she is in a weakened state after getting hit on the head outside. They say at that point she is just trying to survive. She doesn't feel like she is able to take on all of them at once anymore and now is just trying to make it out alive.

As an out-of-universe reason, this is a great opportunity for the showrunners to remind us how sneaky Arya can be. She is indeed a formidable fighter, but she is also very good at remaining hidden and undetected. We get to see for ourselves that she is capable of evading enemies who are mere feet away, which turns out to be extremely important later in the episode when she

leaps from seemingly nowhere to surprise and destroy the Night King.

Without that setup in the library, this feat would have seemed even more implausible.

One of the differences I noticed between her on the wall and her in the library is sound and surroundings.

On the wall, the battle is going on all around and the dead are swarming in all directions. They swarmed around her as much as toward her.

In the library she is alone and the moment she makes a sound every dead in the room (if not every dead in the entire building) will swarm towards the sound of her fighting. You see this happen when she throws a book to distract them and you see over a dozen dead instantly swarm onto the sound.

She could easily kill a handfull or even a few dozen if she had an environmental advantage, such as being on top of a wall. But dozens swarming her alone from every direction is a very bad idea.

From a narrative perspective, it shows that Arya is still human in that she reveals vulnerablity.

This is contrary to the idea of the Faceless Men as implacable, inhuman assassins. (If Jaqen H'ghar were not still mortal, why would he have cared if he was saved or not the first time Arya met him?)

As you noted, the change was from outside to inside the castle. Part of the fear could be that Arya had a mental wall built, anticipating the fight to remain outside the walls. In that sense Wintefell was a parallel for Arya. Once the enemy was inside all rational planning was lost and it was merely survival... It should be pointed out that Arya was quiet enough on her feet in the library that it was the dripping blood that alerted the wight.

Whilst the directors state in a nos bastidores de vídeo that she hit her head and is woozy, I don't see that on-screen. Instead what I see is:

1. She no longer has a long-reach weapon. She is armed only with daggers.
2. She is no longer in the middle of a noisy battle, in a clear area on a rampart with many other humans to help, instead she's alone inside a claustrophobic wooden library, with torches on the wall.
3. The walking dead are not currently aware of her, and she'd like to keep it that way. Should they become aware of her they will all "swarm" at her, as seen later in that scene when they hear the door close and they proceed to chase her in great numbers.

There are limits to her power and she's traditionally not stupid. She's not Thor, this is not Avengers and she's weak after so much fight. Even in tip top shape physically you can psychologically be in pieces just looking around at all that death and the never ending numbers of those wights (not your usual zombies, these folks are fast).

In someways I also think it adds to Arya's whole arc and wanting to set a specific miraculous, but yet disparaging tone for the nature of the story viewers are left with.

There are very few scenes in the epsiode that were nuanced (Arya, Lyanna, Theon, Melisandre, Tyrion & Sansa, Dany & Jorah, Jon and Viserion, Knight King & Bran Godswood), as I think the point of the non-nuanced scenes were there to help the episode subvert the majority of fantasy elements that were initially set up in both the TV series and books by being more realistic.

But Melisandre's scenes were some of the more nuanced scenes too and her story really revolved around Arya's and making Arya "central" or "whole" as she full-circled the episode's story.

Even in the middle of the battle things become literally clearer when things begin to pertian to Arya such as Beric encouraging the Hound to help Arya, but then they pan (still clear) to Lyanna's Mormont's tragic scenes fighting the White Walker Wight Giant, as her story juxtaposes, but also foreshadow's Arya's episode arc, as Lyanna Mormont has always been a shade of Arya.

Symbolism:

Samwell Tarly: That's what death is, isn't it? Forgetting, being forgotten. If we forget where we've been and what we've done, we're not men anymore, just animals...

The interior library scenes also call into the question the importance of the past, immediate (Jon Snow's secret heritage) and far-reaching (Westoros' secret history, the former identity of the Night King, and the true circumstances around his creation), as the over all result of the episode implies that the far-reaching past doesn't matter or spells out doom, as more of it is not revealed and/or nor did the Azor Ahai prophecy come true in terms of meeting certain aspects of it's criteria. So it's very curious that the library is the location of where Arya's fears become more apparent or her confidence is broken.

One also can argue the importance of the interior of Winterfell being a metaphorical "soul" of House Stark and Arya's fear represents the fear that they're all loosing, until she makes her way with Beric's and the Hound's help to a room that feels more 'center', a room with a large fireplace and a "hearth" where she given information to finish her journey seemingly from Melisandre and/or the beyond where her fear is mysteriously once again resolved (IMO there is an element of Gothic story telling with these particular sequences).