There seems to be nothing in the artwork that should be doing this in the vector file, although I'm guessing the explanation is relatively simple.
Vector in Inkscape (before)

Exported .png file (after)

prkos wrote:This seems like a bug but I can't be sure until I see the file in question.
Have you tried breaking up the paths in that word, or simplifying them very little, maybe even delete a node and try to export again, or change exporting resolution?
Try reading here https://bugs.launchpad.net/inkscape/+bug/264090
Very interesting if you still have the original Inkscape svg and you are allowed to post it I would love to try to figure it out.