If you do the same as the Economist and do bit research on Google trends, it's really quite interesting. From 2004 to roughly 2014 the interest in "flat earth" was steadily decreasing. Since then it increased by a factor of about 10. The search interest in "flat earth society" followed the trend for "flat earth" in a 1:1 fashion until 2014. But interestingly the increase since then for "flat earth society" is much lower, about a factor 1.5.
This is for general web search. If you look for searches on YouTube, "flat earth" showed also there an increase in 2014, but since last summer the interest is steadily decreasing, down to 43% from the maximum last year. It's now back on the level as around 2015/16.
For me that shows, that there is indeed an increasing curiosity in the term "flat earth", but it is not really substantial. There is no real increase in engagement into the subject. To watch a video on YouTube cost you much more time than a quick google search looking for an explanation of this term. Also the curiosity leads not in the same way to a kind of institutional interest in something like a flat earth society.
It is also interesting to see, that this mainly a US phenomenon. E.g. the interest ratio between the USA and Russia is 100:3, to the most European countries it is below 100:10. Another thing is, what triggered the interest. And there it seems, that a huge part goes back to some celebrities whose names are the most related search expression to "flat earth".
Doesn't sound like a tide for me...
And I'm also happy to see that the big US universities outnumber the interest in "flat earth" by orders of magnitude... And even my own, comparable small University, generates at least a search interest that is in the same range as that for "flat earth". It's also nice to see, that we get every year more new physics, astronomy, geography, and so on students than people participating on flat earth meetings in the homeland of this "movement". By the way, the yearly meetings of the American Physical Society are joined by more than 10000 scientist every year. And the APS has also numbers regarding membership, it's almost 50000 people... That's a movement...