I come back just to share the actual asnwer. According to the Tekton documentation and this issue (https://github.com/tektoncd/pipeline/issues/7175) I thought that the traces where exported in thrift_http, but it is actually OTLP http. So I just changed the url to http://app-to-kafka-collector.otel.svc.cluster.local:4318 and it started to work :) If someone uses this in the future, please share it here! :)