What seems most likely to me is that some of these had the State Park category on Google Maps for a long time, and now it's being noticed. They say the "Provincial Park" category was removed, which implies it used to be an option.

There's a bit of variation between types of park, even found a provincial park that is labeled both national park and just park, depending on where in the UI you find it.

Images contained in spoiler tag:

Labeling was probably never reliably strictly correct, but removing Provincial Park as a category is a little hostile, considering the timing. (Assuming it used to be an option, and Samantha in the video isn't entirely mistaken.)

...actually, this is at the bottom of the article:

“If you ever see the extremely rare ‘provincial park’ used as a category, this was imported automatically by Google using the old Google Map Maker categories. They have long since simplified the categories (there used to be many hundreds of obscure categories) and provincial park is no longer an option when adding or editing parks,” she said.