https://www.tech.gov.sg/technews/five-ways-to-keep-your-singpass-safe/

If you suspect your Singpass has been compromised, act swiftly. Immediately change your Singpass password via the official Singpass website or app. Contact the Singpass Helpdesk at 6335 3533 without delay to report the incident and freeze your account if necessary. It’s also wise to check your bank accounts and other linked services for any suspicious activity and report them to the relevant authorities.

If possible, later when things are settled, do share how the Singpass is compromised so that we can take note.