Well at the moment pretty much all leisure travel and a large chuck of commuting trips banned by rail are banned so that would suggest the fourth reason accounts for most of the absentee passengers.
However at the end of the summer travelling for whatever reason was permitted, and rail use was still only 40% of normal, while car use was not far off 2019 levels. Therefore there were likely other reasons for the lack of rail passengers at the time.
It would be interesting to speculate how much more growth there would have been had we not started on all the tier business etc.