This is a hybrid text normalization that is context-aware. It is a shallow fusion of non-deterministic WFST and pretrained masked language model, which scores the normalization options suggested by the WFST.
See https://docs.nvidia.com/deeplearning/nemo/user-guide/docs/en/stable/nlp/text_normalization/wfst/wfst_text_normalization.html#text-normalization for details.