Flink Job consuming Google PubSub - DEADLINE_EXCEEDED exception

Question

I'm running a POC in order to get messages from a topic on Google PubSub and process them in a Flink job.

After struggling for days, I was able to finally start getting the messages from PubSub using the PubSubSource from Flink.

Now I'm constantly getting one exception saying:

io.grpc.StatusRuntimeException: DEADLINE_EXCEEDED: deadline exceeded after 14.999285491s. [remote_addr=pubsub.googleapis.com/142.250.125.95:443]
    at io.grpc.stub.ClientCalls.toStatusRuntimeException(ClientCalls.java:262)
    at io.grpc.stub.ClientCalls.getUnchecked(ClientCalls.java:243)
    at io.grpc.stub.ClientCalls.blockingUnaryCall(ClientCalls.java:156)
    at org.apache.flink.streaming.examples.gcp.pubsub.shaded.com.google.pubsub.v1.SubscriberGrpc$SubscriberBlockingStub.pull(SubscriberGrpc.java:1641)
    at org.apache.flink.streaming.connectors.gcp.pubsub.BlockingGrpcPubSubSubscriber.pull(BlockingGrpcPubSubSubscriber.java:73)
    at org.apache.flink.streaming.connectors.gcp.pubsub.BlockingGrpcPubSubSubscriber.pull(BlockingGrpcPubSubSubscriber.java:77)
    at org.apache.flink.streaming.connectors.gcp.pubsub.BlockingGrpcPubSubSubscriber.pull(BlockingGrpcPubSubSubscriber.java:77)
    at org.apache.flink.streaming.connectors.gcp.pubsub.BlockingGrpcPubSubSubscriber.pull(BlockingGrpcPubSubSubscriber.java:77)
    at org.apache.flink.streaming.connectors.gcp.pubsub.BlockingGrpcPubSubSubscriber.pull(BlockingGrpcPubSubSubscriber.java:67)
    at org.apache.flink.streaming.connectors.gcp.pubsub.PubSubSource.run(PubSubSource.java:128)
    at org.apache.flink.streaming.api.operators.StreamSource.run(StreamSource.java:110)
    at org.apache.flink.streaming.api.operators.StreamSource.run(StreamSource.java:67)
    at org.apache.flink.streaming.runtime.tasks.SourceStreamTask$LegacySourceFunctionThread.run(SourceStreamTask.java:333)

...and my job keeps restarting. I can see the messages but I don't know how to get rid of this exception. It happen both locally and in the real Flink-cluster.

Has anybody faced something like this? Any help will be appreciated. Thanks.