What is the maximum idle time for a node to be considered active? Maybe I'm wrong but I remember I read somewhere that a node will be considered active for a certain period even if it is not responding for a certain time (something in the order of minutes).

Does anyone know if this is true?

If this is the case, how long is the maximum idle time for a node?
If there is no traffic on a connection, nodes will periodically send a message to maintain the connection. If a node has not communicated on a connection for more than 90 minutes, it is assumed to be disconnected and a new peer will be found.
A more detailed explanation is given in the book Mastering Bitcoin by O'Reilly Chimera. The specific explanation is given here