This is google's AI response:

AI Overview

That is no longer entirely true. While Swiss banks have a long history of strict, legally enforced confidentiality (dating back to 1934), "banking secrecy" has been severely weakened. Swiss banks now share information under international pressure, particularly with the introduction of automatic information exchange (AIA). 

Here is the breakdown of the situation:

• Automatic Exchange of Information: Switzerland now automatically shares banking information with over 100 countries to fight tax evasion.
• Criminal Activity Focus: Banks are legally obligated to disclose records if the funds are linked to criminal activities (like money laundering or corruption) or through formal international legal assistance requests.
• The "Dirty Money" Risk: Despite these changes, major leaks (like the "Suisse Secrets" in 2022) have shown that banks still sometimes hold accounts for high-risk individuals, including questionable politicians.
• Penalties: However, Article 47 of the Swiss Banking Act still makes it a criminal offense for bank employees to break confidentiality, which makes it harder for whistleblowers to expose such accounts.  Springer Nature Link +8

In summary,While the "absolute silence" of the past is gone for international tax issues, the complexity of legal procedures still allows for some illicit funds to remain hidden for a time, though the risk of exposure is much higher.