FoundationDB was pulled from market when Apple acquired it in 2015.[1] Apple re-released it as open source in 2018.[2] Since FoundationDB is FOSS this time around, it would be possible to fork it in case it becomes unavailable again.
I completely forgot it was initially closed source, and only seriously considered it when it was opensourced in 2018. For the sake of the GP argument, though, I'd say that rebuilt an immense amount of trust in this case. My bad!