Lots of people introduce sentences with an adverb when they should use an adjective. Here’s an example of someone doing it right:
Most important, after more than a decade, puberty was finally done with me.
He didn’t say “Most importantly,” which means “in a most important manner,” not exactly the intended meaning. He means that the event was itself important, not just acting important.
Whenever you see a sentence start with something like “Reportedly,” or “Significantly,” or “Importantly,” you’re probably seeing one of these (incorrect) introductory adverbs.
If you don’t do this, your writing will be tighter and easier to follow.
PS—The linked article that I took the quote from is adult reading. Adult in the adult sense, not the pornographic sense.