What is the hidden fee law?

Excuse me, could you please elaborate on the so-called "hidden fee law"? I'm curious to know if this is a specific legislation that targets undisclosed charges or fees in financial transactions, particularly in the realm of cryptocurrency and finance. Are there any specific regulations that have been enacted to protect consumers from being surprised by hidden costs? Could you provide some context or examples of how this law might apply in practice? Thank you for your insight.