Normally, part of the object of a Raid Battle in Pokemon GO is that the player physically visits a Gym in order to take part in such an event. However, for those still under lockdown as a result of Covid-19, this is obviously impossible. Niantic will address this by rolling out new Remote Passes that can be used at home.
https://www.notebookcheck.net/Niantic-announces-a-new-Remote-Raid-Battle-mode.461821.0.html