To this point specifically: is there any proof this is malicious? Amazon, Facebook, Google have all had outages before; shouldn't we apply Hanlon's Razor when a cryptocurrency exchange fails to serve requests during a massive traffic spike?
Further, an honest exchange makes money on people’s trades. Going down when volume is high means giving up peak profits. Equivalent of amazon reliably going down on black friday.
Making a robust exchange is hard and requires an amazon level of development. Huge movements in price correlate with massive increases in volume. The simplest explanation remains firmly in the realm of poor platform, in my mind, rather than nefarious and illegal manipulation.
Just look at Robinhood. They offer a sleek looking product, but their crypto offering falls down under load (positive and negative) regularly.
First and most importantly, the crypto market can drop 15-20%+ in a 24 hour period; similar rises take multiple days on high-volume, large-cap coins. This is actually not specific to cryptocurrencies, there's a well known phrase in the equity markets "bulls take the stairs, bears take the elevator (or 'the window')".
Similarly, with such volatile assets, when the price falls dramatically, many people are running for the exits. On the other hand, when the price is skyrocketing, many people have a "hodl" mentality, think the price will rise up further, etc. If the price falls off a cliff everyone is trying to sell, but when the price spikes many feel "I missed my chance, better wait for a dip" and aren't rushing to buy.