In original sentencepiece model, white space is considered as a regular character. Please read the description here.

  
      
      github.com
  
  
    

google/sentencepiece - Whitespace is treated as a basic symbol 17


  Unsupervised text tokenizer for Neural Network-based text generation.

  
  
    
    
  
  


I am not totally familier with the huggingface implementation of the sentencepiece. But you can use the original sentencepiece library for that and then try loading that sentencepiece model by huggingface wrapper if needed.