Bro, are you sure it happened this way? I thought that If your Mum had used her CPF funds to purchase the property initially, upon the sale of this property, the amount used + accrued int. by your mum would have to FIRST go back into her CPF.
If she had previously not set FRS by pledging this property, the proceeds of this sale will go into her RA until she has FRS.
After the above is done, your mum (NOT YOU) can withdrew whatever additional balance remaining in her CPF if she’s above 55).
https://www.mortgagesupermart.com.sg/resources/new-cpf-housing-refund-policy
Can you share more in detail on how you refunded your mum’s CPF and withdrew the funds from her accounts?
In your particular case, it means that if a parent/child relationship have a joint tenancy in a property, there may be a loophole where the child is able to take advantage of the situation.
This is concerning.