For fairness purposes, training areas for WOC 2021 were embargoed in late October. Due to government mandated Covid-19 measures, travel to the Czech Republic was not allowed from a number of countries and all athletes did not have the same opportunities for training. The WOC organisers have worked for an exemption and have received an approval from the Czech authorities, allowing athletes from all countries to enter the Czech Republic for training.
Consequently, the embargo is lifted.
More can be read at the WOC 2021 web page.