Variable is not getting substituted in impersonation_chain parameter of GKEStartPodOperator

[Nik77777777]

impersonation_chain:
- "abc@abc-{{ var.value.env }}000.iam.gserviceaccount.com"

impersonation_chain: ["abc@abc-{{ var.value.env }}000.iam.gserviceaccount.com"]

Both above ways of parameter passing of GKEStartPodOperator gives below error (variables passing are working fine in rest of the yaml code and this impersonation_chain thing works in normal python code of dag):
Unable to acquire impersonated credentials', '{\n "error": {\n "code": 400,\n "message": "Invalid form of account ID abc@abc-{{ var.value.env }}000.iam.gserviceaccount.com. Should be [Gaia ID |Email |Unique ID |] of the account",\n "status": "INVALID_ARGUMENT"\n }\n}\n')