decay is deprecated in the new Keras optimizer,

and users are recommended to use a different parameter to achieve similar functionality. The decay parameter was used to apply a learning rate decay over time, but this functionality can now be achieved by using the LearningRateScheduler callback function in Keras. This function allows you to define a custom learning rate schedule that can change over time during training. Additionally, new optimizers such as Adam and RMSprop have built-in learning rate decay functionality that can be used instead of the decay parameter. It is recommended to consult the Keras documentation for the specific optimizer being used to determine the appropriate method for applying learning rate decay.