In the context of cloud computing security, what precisely does it mean to have a shared responsibility paradigm?

Financial institution debit cards are protected by personal identification numbers (PINS). Personal identification numbers (PINS) of this kind typically consist of four digits. Information supplied from ATMs to the computers that verify credit and debit card transactions is encrypted before transmission. A combination of ad hoc management techniques and encryption is necessary for financial organizations to keep data secure. Please provide some light on the reasoning for this prerequisite.

When it comes to security, where exactly are the holes in the architecture?

Is it possible to break cloud computing security in the event of a data breach? In the event that this happens once again, what precautions may be done to avoid it happening again?