Your guess is as good as mine. They're all called Petrichor, all one word, all that spelling. There's also my comic's French version (but that's "Pétrichor (Français)" so probably different enough).
Maybe because it's comics so guidelines assume even with a similar name the difference will be obvious by the cover art and style? Or that it's only one word that has a dictionary definition so you can't really copyright/trademark that on it's own very easily?
Like I don't mind other people having the same title as my comic because I've checked out the other two, one is fantasy and couldn't be confused with mine even if you squint, and the other is a popular long running sci-fi but it's premice is that it's raining all the time, meanwhile mine is that it hasn't rained in years, so as soon as you open the book you'd see a clear difference in the scenery, not to mention visual style and page layouts. I imagine the other two don't mind too much either seeing as they've been peacefully sharing the platform for years before I came by.