I wouldn't call it a sub-compact SUV, but a compact (same as a Seltos or Qashqai or HRV), to me a sub-compact SUV is a vehicle like the Kona or EcoSport or Renegade.
Due to the rapidly rising popularity of CUVs, every manufacturer is creating CUVs of every different size and shape. You really can't think too much about it and have to look at them each individually.
Maybe it's different in Canada, but here in the US, it's sub-compact(CX-3, Soul, Kicks, etc.), compact(CX-5, RAV4, CR-V, Rogue, etc.), mid size 2-row(Blazer, Passport, Murano, etc.), mid size 3-row(CX-9, Highlander, Telluride, etc.), full size(Typically truck based SUVs, like the Sequoia, Tahoe, Expedition, etc)
The Seltos, RogueSport(Qashqai), CX-30, etc. are part of the rapidly growing tweener class; they just get lumped into the traditional classes for simplicity. The Seltos is bigger than the "sub-compact" Soul, but it is smaller than the traditional "compact" Sportage. The Sorento and Sante Fe are now tweeners, falling somewhere between compact and mid size.