PRUNE problem in subquery

Hello,
I found this problem with version 3.6.2 on Kubernetes when subquery contain PRUNE and use an external variable.

Query: AQL: missing variable #11 (iqn4vyso) for node #88 (SubqueryNode) while planning registers (exception location: /work/ArangoDB/arangod/Aql/RegisterPlan.cpp:367). Please report this error to arangodb.com (while optimizing plan) (exception location: /work/ArangoDB/arangod/RestHandler/RestCursorHandler.cpp:298). Please report this error to arangodb.com