The Permissions requirements for Google Pub/Sub as a target state:
pubsub.subscriptions.create on the containing Cloud project (only required if you want Replicate to create a default subscription per topic when no subscription exists).
See Prerequisites.
However, the Pub/Sub endpoint does not offer a parameter allowing the subscription name to be specified.
Resolution
The subscription must follow the same naming convention, which involves appending the "-sub" suffix to the topic name. For example, if the topic name is "mytopic," the subscription name must be "mytopic-sub."
Cause
Qlik Replicate checks for subscriptions that follow a specific naming convention. For example, if the topic name is "mytopic," the subscription name must be "mytopic-sub." Qlik Replicate only recognizes subscriptions that adhere to this naming format.
Environment