madcow.hk: from my comment below :

"Although Nyepi is primarily a Hindu holiday, non-Hindu residents and tourists . Although they are free to do as they wish inside their hotels, no one is allowed onto the beaches or streets, and the only airport in Bali remains closed for the entire day. The only exceptions granted are for emergency vehicles responding to life-threatening conditions and women about to give birth."

There are special constables on the streets making sure no one is violating the curfew.

Nonethewiser: And from that, a quite informative snippet :

"Nyepi is a Balinese "Day of Silence" that is commemorated every Isakawarsa (Saka new year) according to the Balinese calendar (in 2022, it falls on March 3). It is a Balinese celebration mainly celebrated in Bali, Indonesia. Nyepi, a public holiday in Indonesia, is a day of silence, fasting and meditation for the Balinese.

Observed from 6 a.m. until 6 a.m. the next morning, Nyepi is a day reserved for self-reflection, and as such, anything that might interfere with that purpose is restricted. The main restrictions are no lighting fires (and lights must be kept low); no working; no entertainment or pleasure; no traveling; and, for some, no talking or eating at all. The effect of these prohibitions is that Bali's usually bustling streets and roads are empty, there is little or no noise from TVs and radios, limited access to Internet and few signs of activity are seen even inside homes. The only people to be seen outdoors are the Pecalang, traditional security men who patrol the streets to ensure the prohibitions are being followed.

Although Nyepi is primarily a Hindu holiday, non-Hindu residents and tourists are not exempt from the restrictions. Although they are free to do as they wish inside their hotels, no one is allowed onto the beaches or streets, and the only airport in Bali remains closed for the entire day. The only exceptions granted are for emergency vehicles responding to life-threatening conditions and women about to give birth.[3][4]

On the day after Nyepi, known as Ngembak Geni (Relighting the Fire), social activity picks up again quickly, as families and friends gather to ask forgiveness from one another, and to perform certain religious rituals together. Fires and electricity are allowed again, and cooking of food resumes. Nyepi can be traced as far back as 78 A.D."

Maybe harioetama could edit the original post and add the link and info? it is very vague the way it is.

Thank you for sharing this, an interesting custom indeed.