Even pre pandemic, Fridays had become much quieter on the trains from Kent into London, so changes in working practices were already making a noticeable difference.
Since the pandemic hit, the last few times I’ve been on the train up to London, I’ve noticed that off peak services seem to be busier than peak. But I presume that’s because people are making ad hoc journeys and not buying season tickets. Peak trains are prohibitively expensive for occasional travel.
No idea what the long term impact will be for bikes on trains.