Probably because it seems to be less known than Notion. IIRC it's a bit more expensive and more constrainend than notion, more targeted at teams than single users.

I really liked it first impression UI lets see how it goes. Thanks for the share.

Is data removable, do you use?

I use it for personal purpose. By data removable, I guess you mean right to be forgotten. Their https://zenkit.com/en/gdpr/ page provides the details.