I returned to US flying out from Toronto to Philly using AVR. I have an expired F1 visa(expired a year ago) and currently in Day 1 CPT university.
I was flying American Airlines and they checked me in after verifying my passport and my i-20 travel signature date which is valid for one year once signed by DSO.
The usual process that you have at TSA.
The officer checked my visa and asked me why I did not get it renewed as it has been an year since it expired. I mentioned that I was planning to this year but could not travel due to the covid situation. He was getting a problem updating my information. The officer asked me if had proof that I was in Canada only for the last 15 days(Flight tickets/Stay etc). Before I showed them, he said it was ok and did not ask for those details later. He was still getting some issue processing my passport. So, he directed me to a separate Admissibility review area where my passport and i-20 was handed to another officer for review.
The officer who verified my i-20 and passport and started updating in his computer and asked me general questions like below
Where my university was
what was my degree
why I was heading to a different city(My university was in Detroit and I was heading to Indiana) - To this I mentioned that I was doing an internship
If I was on OPT previously - Yes
Confirmed if the I-20 I gave was the latest one
Asked me my reason for visiting Canada - Mentioned PR landing
Also asked me when my degree would be completed and if I plan to return to Canada - I mentioned to him that I plan to move out of US after completing my degree program.
Finally, they took my fingerprints and photo again as it had been a while since I exited US(back in 2015). The whole process took around 20 minutes.
And then they put an entry stamp with date and I was good to go
Note: The officer was very casual and friendly when asking these questions. Not in a serious tone
After boarding, I landed in the US like a domestic traveller. No more immigration checks in the US as Toronto was US Pre-Clearance airport.