Don't double proxy unsafe variables

Potential fix for #12260

lib/ansible/vars/__init__.py

@@ -183,6 +183,7 @@ class VariableManager:
             try:
                 host_facts = self._fact_cache.get(host.name, dict())
                 for k in host_facts.keys():
+                    if not isinstance(host_facts[k], UnsafeProxy):
                         host_facts[k] = UnsafeProxy(host_facts[k])
                 all_vars = combine_vars(all_vars, host_facts)
             except KeyError: