I think similar to Celsius or FTX, they will sell it and they will give back the remaining as cash at the end of the proceeding,
but they will reference it on today's prices so no matter if your crypto in FlowBank appreciates or goes down from now on.
Edit: Celsius gave back around 60% I think in BTC and ETH but they fixed the BTC price to 15k yet they transferred to customers when BTC was already above 30k, so actually users got back only like 30%.