I'm trying to find how to use kubernetes tasks on prefect 2, is that possible? (I mean same as in prefect 1)

No collection contributed yet - you could contribute if you'd like to 🙌

in general all tasks are gone and have to be added again?

all tasks must be migrated to Prefect Collections - don't panic though, @alex made it easy https://docs.prefect.io/collections/overview/#contributing-collections

Hey @Alvaro Durán Tovar! Kubernetes tasks are on our roadmap and we'll begin development of them soon! You can follow development on this repo: https://github.com/PrefectHQ/prefect-kubernetes

👌