In the architecture I'm working on I have a simple SQS queue with a DLQ.
I have noticed a specific behaviour that doesn't make sense in my mind on the DLQ: even if my DLQ has NO lambda trigger it looks like the messages can become not visible sometimes like the queue is trying to process them anyway.
Is it the expected behaviour?
There is anything else (in addition to a lambda trigger) that can make a message not visible in the queue?
In my simple tests, I have just sent a message on the main queue (where there's a lambda attached), in a way that was failing enough times to be moved in the DLQ. From the screenshot above in monitoring, you can see how when the DLQ was holding at some point one message only this started to become not visible 2 times for no apparent reason.