The travel fund meant that you loaded up your SL access card with a sum of money. In March 2023, the access cards at the time became invalid and whether you had money on the card or not, it was done.
On the other hand, the travel fund can be redeemed and you can get the money back, but not many have done that. This means that, for the time being, SL manages a gigantic sum registered in the accounts as a debt to the travelers, something The middle of was first to report on.
In the video you can hear more about how much money is involved and what to do if you still have old access cards.