I got a weird graphical bug lately and at least one guild member reported same:
Spoilers - Recipes
Relogging does not help, however, sometimes it disappears, it is not there on every login. Then it’s back again for some days. Looks like a part of the map is possibly overlaying (which I got turned off). The line also appears when opening lore books.
As visible in the screenshot, one recipe amount number is no longer readable (most others are fine).