Using Notion's name seems like poor form. Describe your product as a clone if you'd like but use a distinct name.
If this intends to become a real project, not only notion.clone is a bad name, it is also clear trademark violation and will be shut down very quickly.
i.e. Nobody's (very few people are) going to be looking for Notion and then be happy finding this instead, it seems to me more like I might use it as well, liking Notion's editor, but not wanting all of my/plain notes in Notion itself.
Edit: I should probably add that I think people vary quite heavily in how they use Notion - I've previously been berated on HN for comparing it to Airtable, since to me the defining feature and main use is the tables/cards/database/multi-views on to the same data, but others it seems just use it for 'pages' and I suppose perhaps page hierarchy as part of that.
Just lifting the name of a product you're cloning to register a .clone TLD is simple, but it also inherently means that no one else can, and that's sort of problematic in the face of shipping something you're explicitly describing as a copy.
But this is clearly someone stretching their legs on a tech stack with an homage to Notion.so, not a competitor
I mean they literally recommend the original in the first pargraph:
> This clone tries to replicate some of the great note-taking features Notion has. If you don't know Notion.so yet, I highly recommend to check it out!
The demo is just that, a demo. There's a very clear precedent for this sort of naming for tech demos that reimplement a product in a new tech stack
Spam was a trademark, it came into common use - it was no longer a trademark.
Not really, no.
> This doesn't look like a finished product meant for the public so it's fine I think.
Not how trademarks work, AFAIK, although IANAL.