You can subscribe multiple lambdas to an SQS queue. It's not recommended, but it's doable. many-to-many or many-to-one depends on your choices of infrastructure.
I guess we can debate the semantics of it because it is technically possible. But it is terrible design to have a SQS to many different consumers. If someone did that I would reject it on review. In any proper usage of SQS it is many to one.
there are edge cases where that's desirable. I won't enumerate them here but they're discoverable on the Googles. I also would advise against that kind of passionate adherence to infrastructure dogma, taking a more analytical approach to review.
If you could name even one I would remove the "dogma". I cannot think of why anyone would want to do that. And if someone did want to do that they would have to have a very compelling reason to complicate what is usually an easy thing (One action listening on a queue)
I am not referring to multiple homogeneous consumers processing a queue. That is fine. You have a pool of consumers that can pick up from the queue. That is still considered one entity/actor. The people here are proposing having multiple heterogeneous consumers consume from the queue. That is bad.