These Mysterious billboards are dropped in Varanasi, India. Varanasi is a highly sacred place and considered as the spiritual capital of India. The movie title is also based on the same place, so yeah certainly the billboards are about Varanasi movie's release date.
It is the first non-English movie to be shot in True IMAX 1.43 aspect ratio, so IMAX must be looking to push it. IMAX also dropped a 1.43 trailer for any movie for the first time with Varanasi – https://youtu.be/odDvRxuP2wQ
by cricinephile