let cat out of the bag vs unmask

let cat out of the bag

unmask

verb
  • To cease engaging in masking, to cease disguising one's autism. 

  • To enable (an interrupt, etc.) by unsetting or setting the associated bit. 

  • To remove a mask from someone. 

  • To expose, or reveal the true character of someone. 

  • To remove one's mask. 

How often have the words let cat out of the bag and unmask occurred in a corpus of books? (source: Google Ngram Viewer )