Context: LaTeX is a typesetting system. When compiling a document, a lot of really in-depth debugging information is printed, which can be borderline incomprehensible to anyone but LaTeX experts. It can also be a visual hindrance when looking for important information like errors.
Most probably a narrow column with a word near the end that TeX had problems hyphenating.
A line of text is basically a hbox. The words in this line are fixed in their lenght, so TeX distributes the space between them as evenly as possible to fill this hbox. It has a certain range for the length of a space, and tries to move words or parts of words with hyphenation around to stay in the OK range for the space width. If it can’t, it complains about under- or overfull hboxes.
I ran into this issue when using code blocks in LaTeX that contained a bash command like ‘echo aBcdEF32… > /var/www/index.php’, where aBcdEF32… was the base64 encoded string of a web shell. I wound up having to set the line break behavior to split on some random letters/numbers to get everything to wrap appropriately, although that was probably some hacky heretical solution.
You could have used a thin space every four or eight hex digits, showing that it is not really a space but making it easier to read.
But you cannot blame TeX for not being able to break such a construct.
