>>717170072
Just because an engine has a lineage to it, does not mean it isn't "in-house".
Bethesda's last Gamebryo proper game was Fallout 3, and ever since then they've made a fork and are no longer affiliated with Gamebryo. In fact, that's very likely the reason they still work in Creation Kit, because it's "theirs" now, and they don't want to fork over cash to license an engine like UE5.