I was unable to find the answer for this question, so after (at least partly) figuring it out, I decided to post this to help others.
I was unable to figure out what the first part of the log lines was. Most of the lines read [N65K3]. And it took some time, and some futile googling, before I realized that it was the first five characters of the unique ID of the device (my laptop). I thought it was some service/library/function.