It looks like the door with missing symbols is

>! A water and filled circle  
>! [![Solution][1]][1]

We have the [tag:pattern] tag.

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Looking from the top right symbol, we have a hint:

>! I interpret this as "Backwards correct"

Looking from the leftmost door (X and square) and the symbols in the top, we can see

>! Something's common: **the square** in the symbols and the door.

The next door has a symbol of filled circle and broken outlined circle. Seeing this and the top one again,

>! **The broken outlined circle is common**.

Continuing,

>! The airport symbol is common in the right door and the symbols. This means our next pattern will be a **water symbol.**

What about the cross and the filled circle?

>! That's obvious: Cross in left, filled in left, cross in right, and our next pattern should be **filled in right.**

Yet I don't know how will the [tag:cipher] tag will work for this one.

  [1]: https://i.sstatic.net/8Jkj8.png