Functionbeat cannot process more than 1 message from pub/sub

Hello,

Since 7.11 up to 7.15, I cannot configure functionbeat to process more than 1 message.
I deploy functionbeat on GCP cloud function.

Every first message send to cloud function will be properly traited and sent to my Elastic Cloud cluster. Every second message sent to functionbeat will result in a panic crash.

2021-10-04T14:30:22.827Z FATAL [functionbeat] instance/beat.go:171 Failed due to panic. {"panic": "name version already used", "stack": "pubsub/vendor/github.com/elastic/beats/v7/libbeat/cmd/instance.Run.func1.1\n\t/workspace/src/pubsub/vendor/github.com/elastic/beats/v7/libbeat/cmd/instance/beat.go:172\nruntime.gopanic\n\t/usr/local/go/src/runtime/panic.go:965\npubsub/vendor/github.com/elastic/beats/v7/libbeat/monitoring.panicErr\n\t/workspace/src/pubsub/vendor/github.com/elastic/beats/v7/libbeat/monitoring/registry.go:257\npubsub/vendor/github.com/elastic/beats/v7/libbeat/monitoring.(*Registry).doAdd\n\t/workspace/src/pubsub/vendor/github.com/elastic/beats/v7/libbeat/monitoring/registry.go:159\npubsub/vendor/github.com/elastic/beats/v7/libbeat/monitoring.addVar\n\t/workspace/src/pubsub/vendor/github.com/elastic/beats/v7/libbeat/monitoring/metrics.go:225\npubsub/vendor/github.com/elastic/beats/v7/libbeat/monitoring.NewString\n\t/workspace/src/pubsub/vendor/github.com/elastic/beats/v7/libbeat/monitoring/metrics.go:170\npubsub/vendor/github.com/elastic/beats/v7/libbeat/cmd/instance.Run.func1\n\t/workspace/src/pubsub/vendor/github.com/elastic/beats/v7/libbeat/cmd/instance/beat.go:182\npubsub/vendor/github.com/elastic/beats/v7/libbeat/cmd/instance.Run\n\t/workspace/src/pubsub/vendor/github.com/elastic/beats/v7/libbeat/cmd/instance/beat.go:197\npubsub.RunPubSub\n\t/workspace/src/pubsub/pubsub.go:35\nreflect.Value.call\n\t/usr/local/go/src/reflect/value.go:476\nreflect.Value.Call\n\t/usr/local/go/src/reflect/value.go:337\ngithub.com/GoogleCloudPlatform/functions-framework-go/funcframework.runUserFunctionWithContext\n\t/workspace/src/github.com/GoogleCloudPlatform/functions-framework-go/funcframework/framework.go:202\ngithub.com/GoogleCloudPlatform/functions-framework-go/funcframework.runBackgroundEvent\n\t/workspace/src/github.com/GoogleCloudPlatform/functions-framework-go/funcframework/events.go:101\ngithub.com/GoogleCloudPlatform/functions-framework-go/funcframework.handleEventFunction\n\t/workspace/src/github.com/GoogleCloudPlatform/functions-framework-go/funcframework/framework.go:169\ngithub.com/GoogleCloudPlatform/functions-framework-go/funcframework.registerEventFunction.func1\n\t/workspace/src/github.com/GoogleCloudPlatform/functions-framework-go/funcframework/framework.go:136\nnet/http.HandlerFunc.ServeHTTP\n\t/usr/local/go/src/net/http/server.go:2049\nnet/http.(*ServeMux).ServeHTTP\n\t/usr/local/go/src/net/http/server.go:2428\nnet/http.serverHandler.ServeHTTP\n\t/usr/local/go/src/net/http/server.go:2867\nnet/http.(*conn).serve\n\t/usr/local/go/src/net/http/server.go:1932"}

I've tried any workaround I could think of but none of them worked.
One workaround is working tho. It consist to activate the retry feature on the cloud function but this behaviour is generating a very high amont of instance spawn and it doesn't perform well.

Do you reproduce this issue too ? Do you have a workaround or a fix ?

Thank you in advance