ISO codes are lame anyway. Even the 3 letter codes are insufficient for extant human languages (let alone the extinct ones that we have enough of a corpus of to classify). Yeh, yeh, I know 18,000 sounds like it's enough, but not when the impulse is to make it an abbreviation for the endonym.
Frankly, if Mel Gibson would quit making movies where there's no 3 letter code for the depicted language, I could probably ignore this entirely. But that's what started my deep-dive into this stuff. From there, I went on to even getting some listed in the Conlang Registry.
I guess someone needs to contact the Conlang Registry and have them de-register qtk.