As reported by our sister site Deadline, Penn made clear his stance to producer UCP upon returning from the Cannes Film Festival premiere of Flag Day, a film he directed and stars in alongside Katheryn Winnick (Big Sky), his daughter Dylan Penn, and Josh Brolin. Penn reportedly has a couple weeks' worth of filming left on Gaslit.

Current COVID safety protocols in Hollywood, which were the product of much negotiation with assorted unions, only afford producers "the option to implement mandatory vaccination policies for casts and crew in Zone A on a production-by-production basis," Deadline notes. (Zone A includes where unmasked actors congregate and perform on set, surrounded only by key crew members.)