hey @supermathie thank you for looking into this!
the post history is not restricted by admins in this case. otherwise the initial versions shouldn’t be available through the API, and they are, like I linked above.
I believe this was caused because this user made an edit and pasted the contents of a google doc in there. I think there might be some character that was pasted, that corrupted the data.
if you could look into it that would be great!