49ers will host the Bills and Washington in the Cardinals' stadium in Weeks 13 and 14 due to COVID-19 restrictions.
Both games were scheduled to be played at Levi's Stadium in Santa Clara but local health officials shut down all collegiate and professional sports in the area due to Covid concerns. State Farm Stadium in Arizona has only recently begun allowing friends and family (and not the public) into home games, keeping travel from 49ers fans at bay at this time. There's still a chance the Niners return to Santa Clara for its season finale (and final home game) against the Seahawks on January 3.
A lot of mostly-left people just don't like football, and rather than just let others enjoy it as either participants or spectators, they just want to ban it because they don't like it.
Somehow, these same people won't say a word about the Covid dangers of protest mobs and looting sprees, and want bars and restaurants closed, but their pet ideologies must be protected.