I found this to be very suspicious.
I had only read the negative reviews on the legal motions I linked above, but after your comment I also went to Glassdoor to have a look at the positive ones. As you say, they all look very suspicious. The "Cons" section of many of these reviews is nonsense, and contains more "Pros" in disguise. Things like:
"Sometimes want to keep working and need to remind myself to take a break!"
"You can get addicted working with this company - with high energy, lovable team members."
"Pretty much the dream job for me"
"The company is growing too fast."
It does seem like Kraken leadership are either posting reviews themselves, or maybe incentivizing employees to leave positive reviews?
It is understandable that Kraken had to downsize, and it is understandable they had to cut off access immediately.
From reading the reviews, it doesn't sound like this was an isolated incident though. If they don't like you or you don't "fit with their culture", they just cut your access and email you to say you are fired. They give no reasoning and no explanation, and they use this process as a threat to existing employees. Hugely unprofessional.