I dunno if this is relevant, but I noticed the recent new version of UOB app suddenly could detect root.
However, I did not give up, and checked the Magisk Denylist. I found that the app recently added a new string that has got something to do with Zygote, namely com.uob.mighty.app_zygote. Once I added that to the DenyList the app no longer detects root and I am able to do banking liao.
I still have not updated the SingPass app unless I am forced to update when they cut access to the earlier version, so perhaps those of u with the newest SingPass app try to check your Magisk DenyList see if there is a similar new string that has to be enabled in the DenyList?