The PDPA does not ban overseas storage. It sets conditions.
A common misunderstanding is that Singapore law requires personal data to stay in Singapore. The Personal Data Protection Act does not say that. What it contains is the Transfer Limitation Obligation in section 26, which the PDPC's Advisory Guidelines on Key Concepts in the PDPA summarise this way: an organisation must not transfer personal data to a country or territory outside Singapore except in accordance with the requirements prescribed under the PDPA.
In practice, the guidelines explain, this means ensuring that personal data transferred overseas is protected to a standard comparable with the PDPA. Data can go abroad. The organisation sending it has to be able to show that it stays properly protected when it does.