Why does this kind of screen chenge color at different angles?

That looks like a type of Thin film interference, like you’d see on an oil slick or a soap bubble. Wikipedia says:

Thin-film interference is a natural phenomenon in which light waves reflected by the upper and lower boundaries of a thin film interfere with one another, either enhancing or reducing the reflected light.

I’d guess the display uses a thin film on one of its layers causing this rainbow interference pattern that shifts depending on viewing angle.

First of all, hi fellow Romanian :)

Second, it might be a TN panel: cheap, but it changes colour a lot at a angle

Fundamentally, LCD displays like this work by controlling which pixels are dark or light by having polarised light coming from behind (the yellow glow) and then blocking it by switching the polarisation of liquid crystal at a pixel-by-pixel level.

When the liquid crystals are aligned with the light the light gets through to your eyes, when unaligned the light is blocked.

As viewing angle increases, increasing amounts of light leaks though ‘dark’ pixels, because the liquid crystal is no longer effectively blocking it at that angle.

That’s my simplistic understanding

It's a bunch of cheap LCD monitors stringed together, you can see their edges. They tend to have very poor viewing angles, the image starts shifting color hue as soon as you move off-center and it becomes impossible to see as you approach 180° (seen in your pic at the far end). But it doesn't matter in this case because the writing is very large and most people will look at them head on. It's actually a very good use of cheap LCD panels.

A good explanation of the different thin film transistor (LCD) panel types:

https://tftcentral.co.uk/articles/panel_technologies

Yes

@sarmale poor maintenance maybe? Does it look all blue with white text when sitting right in front of it? Or is it yellow-tinted as well? In Brașov I saw the screens looking like that. In Bucharest at the main departure/arrival board (in Gara de Nord) they looked more blue (whether this is due to better maintenance or because they are newer, I don't know).

For any international audience: these screens have become quite common in our train stations in Romania as of late, and they show the train arrivals/departures.

Unde-i asta, boss?

It's obviously magic. Muggles 🙄