I'm dealing with the exact same issue. I want a contact to be automatically re-assigned to the original (marketing) owner, who assigned it to a (sales) owner, when sales rejects the contact.
So I need a field with last owner. I found a way to have a field available with the last owner value (this is a bit tricky to build). But the Change Owner flow step does allow that field value to be used and creates an error. So even when you're able to store the value, you can't use it.
This leaves we to the conclusion it has to be done on the Salesforce end. APEX trigger or so.
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