It seems the Celery queue defaults to AMQP, but arguably shouldn't even try connecting if it isn't specified.
[2022-06-17 20:04:05,216: DEBUG/MainProcess] | Worker: Starting Hub
[2022-06-17 20:04:05,219: DEBUG/MainProcess] ^-- substep ok
[2022-06-17 20:04:05,219: DEBUG/MainProcess] | Worker: Starting Pool
[2022-06-17 20:04:05,226: ERROR/MainProcess] consumer: Cannot connect to amqp://guest:**@127.0.0.1:5672//: [Errno 111] Connection refused.
Trying again in 2.00 seconds...