Current Twt Hash spec and probability of hash collision:

The probability of a Twt Hash collision depends on the size of the hash and the number of possible values it can take. For the Twt Hash, which uses a Blake2b 256-bit hash, Base32 encoding, and takes the last 7 characters, the space of possible hash values is significantly reduced.

1. Base32 encoding: Each character in the Base32 encoding represents 5 bits of information (since ( 2^5 = 32 )).
   
2. 7 characters: With 7 characters, the total number of possible hashes is: