I've heard an accent that has trouble pronouncing the English "th" sound, instead approximating it with more of a "t" sound that misses the tongue thrust. Maybe that is what's happening here?

Since the misspelling was repeated, this could actually be a helpful comment.

Sorry about that, I'm not a native speaker so I sometimes confuse words that sound similar. Grammarly is usually pretty good about pointing stuff like that out, sadly it failed me this time.