Fake news.
Care to elaborate?
The article starts off explaining the lack of reliable data sets. And most of the stuff in the article was either anecdotal (like some company that took 3 groups of people around Europe looking for places to move, and now projects to have 57 groups) or % stats (which are quite meaningless without the baseline).
Not exactly fake news, but not solid info either...
We will know a lot better in 2030 when we do the census.
That isn't right. It notes the U.S. government doesn't collect comprehensive statistics, then it does a decent job citing many alternative data sources that all point the same way: A Brookings Institution estimate, trends over time from National stats of Portugal, Ireland, France, and some scattered datapoints from Spain, Netherlands, UK, Czech Republic, renunciation of citizenship numbers.
Even if it was purely % stats, you don't need a baseline figure for the claim in the headline (Americans are leaving the US in record numbers) just that the number is going up. There's plenty of solid info that this is a real phenomenon. What's uncertain is the magnitude and significance of it.