To get the technical information out of the way: I'm playing on PC, Steam version, with Primal Calling and Lost Valley DLCs. Game version is 1.3.82 b - Public.
For this playthrough I mostly sided with the Forge and the People factions, but in the end I decided to fight my way through the redeemers. When my party leaves the redeemer's cave, only the first screen of the ending sequence triggers where it say something like "You finally managed to leave the valley and return to Masgarth." However, after that the screen goes black and the game freezes. Nothing about who is or isn't on the throne, nothing about where Marin Ving is, nothing about the research complex. It's just a black screen, no sound, nothing, the game just freezes there.
There was no such freeze in a previous playthrough of Lost Valley where I sided with the people and went for the good ending (re-unified Orenetis-Sitenero on throne, getting out of the valley with the magical item that controls the redeemers).
Update (2022-07-26): This freeze still occurs with the version 1.3.85 - Public, but background sound keeps playing during the freeze.
Update (2022-07-26), part 2: For reference, there is an older thread by someone else describing the same bug: Leave the Valley for Nothing
"From then on, when anything went wrong with a computer, we said it had bugs in it." - Grace Murray Hopper
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