By default, a topic's access rights are the same as the map it belongs to. In this scenario, to get a topic's access rights, it is necessary to get the rights of the related map.
However, if access rules for topics are activated, it is possible for topics to have different access rights from the map they belong to. For example, an internal topic inside a public map. In this scenario, it is not possible to get the access rights of a topic through the Fluid Topics API.