I recently revisited some material that I had studied some years ago but had put it aside, and had largely forgotten about it. The material was the Gospel of Thomas. When revisiting the material this popped out.
https://www.sacred-texts.com/chr/thomas.htm
"
There has been much speculation on the relationship of
Thomas to the canonical Gospels. Many Sayings in Thomas have
parallels with the New Testament Sayings, especially those found
in the synoptic Gospels. This leads many to believe that Thomas
was also based on the so-called "Q" Document, along with Matthew,
Luke, and Mark. Indeed, some have speculated that Thomas may in
fact be "Q". Unlike the synoptic Gospels, and like "Q", the
Gospel of Thomas has no narrative connecting the various Sayings.
In form, it is simply a list of 114 Sayings, in no particular
order. Comparison with New Testament parallels show that Thomas
contains either more primitive versions of the Sayings, or
developments of more primitive versions. Either way, Thomas seems
to preserve earlier traditions about Jesus than the New
Testament."
The above led me to this: https://en.wikipedia.org/wiki/Q_source
And then this: https://en.wiktionary.org/wiki/Quelle
Q standing for "Source" makes more sense than Q standing for "Q clearance", which I have always thought somewhat silly. And it gives some context on what "Q" represents in another perspective. And of course, I am not saying "Qanon" has anything to do with religion.
I am just offering another source where "Q: may come from since it already is in common usage in another context.