The fourth season of Stranger Things, famous series Netflix designed by Duffer Brothers, has currently been put on hold due to the rampant coronavirus epidemic, thankfully as a simple precaution. It is in fact important to protect the cast of the production and avoid dangerous moments of close contact, especially if these do not take place with the necessary protections as obviously happens during all recordings.
It is not yet known when Stranger Things season 4 will be ready for the debut, but it is unfortunately likely that this stop of filming could cause a more or less serious delay of the date not yet announced.