What happened to ng

The short answer: the alphabet list changed, the text did not.

What actually changed

The old alphabet had 26 letters and three digraphs: sh, ch, ng. A digraph is written with two characters but stands for one sound.

In the new alphabet sh and ch were replaced by ş and ç, one character each. They are letters now, not digraphs. No separate character was introduced for ng, so it simply lost its digraph status.

The result: 28 letters and the tutuq belgisi ʼ.

What happens to the text

Nothing. singil, keng, tong — all still written with the same two letters. Run them through the converter and you will see they come back unchanged.

The difference shows up in exactly two places: when you count the letters of the alphabet, and when you sort a word list. ng used to be one unit; now it is n and g, two ordinary letters.

Why it was done this way

There is no official explanation, so we will not guess at one. The practical side is clear enough: nobody ever misspelled ng, because there was no other way to write it. The reform touched the three marks that were a problem in practice.