Convert tensorflow code from old version to new version of the library

I have the following custom trainer in tensorflow code (1.14).

Weights loading problems with custom TF model

I encountered the problem on Google Colab, TF version: 2.16.1, keras version: 3.3.3

tf.data.Dataset.shuffle() vs shuffle during tf.data.Dataset.sample_from_datasets

I have plenty of tf.data.Dataset and want to shuffle the contents during each epoch. I load them as follows: