The website you link is not the Pix specification put out by the Brazilian government. Rather that is a payment integrator building services on top of the government spec.

Their specs are published here: https://openbankingbrasil.atlassian.net/wiki/spaces/OB/overv..., with the main landing page for the program is here: https://www.bcb.gov.br/en/financialstability/pix_en