Just be careful. The trip credit you get can only be used on NEW bookings. So if, for example you change your flight to a less expensive one or the price goes down by $200, and then later you change again and the price goes up by $200 you will have to fund that with NEW money, you can’t use that trip credit. It’s disingenuous and dishonest IMHO, and if this had happened to me on a personal ticket (vs a corporate travel agent issued work trip) I’d be making stronger waves.

I think there are (sketchy) workarounds but still…