I'm suggesting one or more of the authors and whoever proofread this article before publication do not understand limit order books, and they therefore don't understand this particular market at the micro level.

Everything they have highlighted in the red and green graphs in the latter half of the article can be explained by a completely ordinary order flow. Much weirder stuff happens in the order books every day: iceberg orders that appear small but are bottomless, giant walls that retreat as soon as they're touched, spoof orders that are placed and canceled repeatedly. None of that funny stuff is in evidence here.

Let's focus on one particular error from the article and I'll explain the misunderstanding behind it. Take a look at the diagram titled "Tether-USD Trades on May 9 From 20:59:13 to 21:01:00 GMT." If you don't understand the two prices of a limit order book, you might think that diagram shows 7 different price movements. But in fact, there are only two price movements: when the Ask price moves from .9991 to .9992, and when the Ask price moves from .9992 back to .9991. Something to remember about limit order books: market buy orders will execute at the Ask price, which is at least one increment higher than the Bid price. Market sell orders will execute at the Bid price, which is at least one increment lower than the Ask price. Why can't the Ask and Bid prices be the same? If you had a limit buy order on the books at $100 and a limit sell order on the books also at $100, they match to each other, cancelling each other out until only one type of order (buy or sell) is left at the contested price. When looking at a price history graph like this, what is actually plotted is the Last Executed Price. If the Bid and Ask prices are completely static, the price history will show oscillation between the Bid and Ask prices as market buy orders and market sell orders are executed in turn. The gap between the Bid and Ask prices at a point in time in the order book is called the Bid-Ask Spread. An important point is that when the Bid and Ask are not moving, the Last Price graph will still show oscillation across the Bid-Ask Spread.

So now look again to the diagram caption: "Multiple sell orders of exactly 13,076.389 are executed, and the price didn’t budge..." What this means is that there was more than 183,076.46 in buy limit orders at the Bid price of $0.9990, which is fairly typical to witness. Certainly not evidence of manipulation or even out of the ordinary. The second caption "...but a buy order of just 75 moved the price up .0001" is more problematic. Neither the Bid price nor Ask price has actually moved in response to the size 75 order, this is just the normal oscillation across the Bid-Ask Spread. Furthermore the minimum price increment on Kraken is 0.0001, so the minimum any buy order following a sell order can move the Last Price is 0.0001 (barring a simultaneous drop in the Ask price.) Let me repeat: Unless the Ask price drops, any and all buy orders following a sell must move this price graph upward by at least .0001 by definition. This appears to be lost on the authors, who highlight the .0001 move upward as something notable, an outsized price move for such a small order. They might be shocked to discover that a size 0.01 order would also move the price graph upward as much as the size 75 order.