Both of those articles are based on the same report, which shows a 500% increase in the US from 2014 till now. 1% identified as vegan in 2014 and now it's 6% of Americans. So the second article probably got mixed up by the 6% and said 600% instead of 500%. However, those numbers don't look like any other I've seen over the years. Gallup poll surveys are usually the most accurate. They had 2% vegan in 2008 and 3% in 2018. That's only a 1% rise in 10 years. Also, 5% say they are vegetarian, which hasn't really changed. The numbers might be a little more, but not by much. I don't know about the other countries.
https://news.gallup.com/poll/238328/snapshot-few-americans-vegetarian-vegan.aspx
https://news.gallup.com/poll/238328/snapshot-few-americans-vegetarian-vegan.aspx
There are more vegetarian eateries and food options these days though.