RE:re: shelf filing .. Shelf prospectus filing / registration is a common practice to permit multiple offerings on the one registration and to get the paperwork out of the way.. Yes they did the same thing in Feb 2019. So what is the key difference between the new and the old filing? Back in 2019 the shelf prospectus was not registered with the SEC (under the United States Securities Act of 1933). The 2021 shelf prospectus has been filed with the US SEC. Surely because of the listing on Nasdaq.
In summary: It is the same shelf prospectus except that the old filing was purely Canadian and the new one is needed to also include the USA.