When when IRCC tries to query the CBSA's database, they will only see the entry record into Canada (20-Nov-2019). They will NOT be able to confirm when the applicant left the country. This is the reason why a lot of applicants get asked for all the pages of the passport because those pages will show the real picture (Singapore Immigration would have stamped your passport on 10-Jan-2019 with an entry stamp and by looking at this, IRCC will be able to confirm the applicant lied on their physical presence calculator).
Asking out of curiosity. How would they confirm whether the Physical Presence calculation is correct when it comes to applicants moving between Canada and their country of citizenship? e.g. if CBSA used to not track exits, and you don't get entry stamps for your country of citizenship, literally the only data point they'd have is when the applicant re-entered Canada? The applicant could've technically lived outside of Canada for years and only claimed a single day in their calculation.