Problem using chain within httpjson input

Dear community,

as soon as we configure a chain task within the httpjson input we receive the following error

{"function":"github.com/elastic/beats/v7/x-pack/filebeat/input/httpjson.run.func1","file.name":"httpjson/input.go","file.line":178},"message":"Error while processing http request: error while getting keys: parsing error: \t - 1:1 unexpected EOF while scanning extensions"

When leaving out the chain step, and just use 1 request, everything is just fine.

Although we are using 8.14.2 we find it awkward the logs are mentioning v7 within the logs?

filebeat.yml

filebeat.inputs:
- type: httpjson
  enabled: true
  #request.tracer.filename: /var/log/filebeat_api_debug
  interval: 7s
  request.url: https://w.x.y.z/token/
  request.retry.max_attempts: 3
  request.timeout: 10s
  request.method: POST
  request.ssl:
    - enabled: false
  request.transforms:
    - set:
        target: header.Authorization
        value: 'Basic xxxx'
  chain:
  - step:
        request.url: https://w.x.y.z/endpoint1/
        request.method: GET

Filebeat version: 8.14.2

I think I solved the problem by using the required key 'replace'