One of the problems with sentences provided to LLMs is that they may refer to specific subjects, and could potentially be part of the training set. For example the following is considered extremely difficult :

> oJn amRh wno het 2023 Meatsrs ermtnoTuna no duySan ta atgsuAu ntaaNloi Gflo bClu, gnclcinhi ish ifsrt nereg ecatkj nad ncedos raecer jroam

When you perform a google search for just 2023 Meatsrs, you can find a very similar sentence, and you could decipher the sentence very quickly …