I think it's just a what you know sort of situation.
If you've used sync for years, the interface, shortcuts etc feel intuitive even though that is caused by hours of practice/experience.
Personally, coming from another reddit client, all the Lemmy apps/interfaces I've tried still feel a bit awkward even after a month or whatever.
The uncanny issue may also be causing a problem. While Lemmy is different, the basic idea (communities, posts etc) is very similar to reddit. Something that is similar but slightly different can feel uncanny, which is often unsettling/frustrating.