Is it something that has yet to come? And who gets anything put on their forehead? Might it be a bandana? Very strange. Here are a couple of verses from Revelations that discusses the "mark of the beast".
Revelation 13:16-17
And he causes all, the small and the great, and the rich and the poor, and the free men and the slaves, to be given a mark on their right hand or on their forehead, and he provides that no one will be able to buy or to sell, except the one who has the mark, either the name of the beast or the number of his name.
Revelation 14:9-10
Then another angel, a third one, followed them, saying with a loud voice, “If anyone worships the beast and his image, and receives a mark on his forehead or on his hand, he also will drink of the wine of the wrath of God, which is mixed in full strength in the cup of His anger; and he will be tormented with fire and brimstone in the presence of the holy angels and in the presence of the Lamb.
Source: https://bible.knowing-jesus.com/topics/Mark-Of-The-Beast
Revelation 13:16-17
And he causes all, the small and the great, and the rich and the poor, and the free men and the slaves, to be given a mark on their right hand or on their forehead, and he provides that no one will be able to buy or to sell, except the one who has the mark, either the name of the beast or the number of his name.
Revelation 14:9-10
Then another angel, a third one, followed them, saying with a loud voice, “If anyone worships the beast and his image, and receives a mark on his forehead or on his hand, he also will drink of the wine of the wrath of God, which is mixed in full strength in the cup of His anger; and he will be tormented with fire and brimstone in the presence of the holy angels and in the presence of the Lamb.
Source: https://bible.knowing-jesus.com/topics/Mark-Of-The-Beast