Now that the longs had their say, here is the short side.
Shopify has an API. Someone wrote a plugin to allow a shop keeper to publish inventory into the Walmart API. When sellers sell on Walmart's platform, Shopify sees zero transactional revenue.
That's the actual technical story.
The linked "article" which actually included a quote from the COO includes a page of bullet points about how Shopify is really knocking it out of the park. Including the "Facebook deal".
Actually the Facebook deal is FB pulling the cart & payments features into their FB & Instagram apps. So, effectively killing Shopify web store use. Apparently FB is doing something special for Shopify so that Shopify can charge 2% on top of FB's 5% fee. But sellers can also just make their shops directly on FB and skip the 2% Shopify surcharge.
I would have expected fellow programmers to understand a bit of math & show some constraint with bubble valuation stocks!