It’s been a while since I looked into it, and things might have changed since then, but some stuff off the top of my head:
Apart from that it’s somewhat politically questionable, based in Dubai (I think), with dubious financial backing and Russian developers. Because it’s closed source and the encryption is proprietary, there’s no way of knowing how much info it leaks.
Because you, as an employee, have a choice. Have you been asked to do something unethical, something that violates your principles?
That happened to me in my previous job. I told my team and reported it to my superiors. My refusal got me a personal audience with the CEO. But when another thing happened that got me asking around. And when that guy got promoted, our whole team left.
Hey look everyone, we got a dirty belter here!