Every year, works from different fields, visual arts, literature or film and more, enter the public domain. What does that mean? Public domain means that these works no longer have a rights holder. In Germany, this occurs 70 years after the death of the author.
A list of the authors concerned is available on Wikipedia: https://de.wikipedia.org/wiki/Wikipedia:Public_Domain_Day/2021_in_Public_Domain This year, for example, Max Beckmann or Heinrich Mann are included. However, this does not necessarily mean that the works can be found on the internet or are actually freely accessible. Museums in particular claim reproduction rights, which is why accessibility is nevertheless made more difficult.