Siebe said: “What happens with an arahant after dying?”
You can ask the same question in many ways. But you get the same answer from the Buddha, per Tipitaka. The same thing happens to an Arahant, as to what the Buddha said what will happen to him.
I am copying my reply to you in the “The Infinity problem – BIG doubt” topic:
In his very first desana, the Buddha clearly stated that in order to stop all future suffering, the goal of any person should be what he had attained. Dhammacakkappavattana Sutta (SN 56.11): “..Ñāṇañca pana me dassanaṃ udapādi: ‘akuppā me vimutti, ayamantimā jāti, natthi dāni punabbhavo’”ti.”
Translation: “..The knowledge and vision arose in me: ‘Unshakable is my liberation. This is my last birth. There is no more renewed existence for me.”.
How more clear can one be?
And there are many more suttas stating this clearly.
The concept of Nibbana has been explained in many posts, including in the subsection: “Nibbana“,and in the post, “What Reincarnates? – Concept of a Lifestream“.
Answers to your questions can be found in those posts and elsewhere in many posts. We also discussed these, over and over, under different topics in this forum.
You do need to stop pushing your philosophical ideas at this forum. That takes the focus away from useful discussions. I am going to remove you as a forum participant if you post again like this without citing evidence from the Tipitaka. If you have evidence to the contrary, you can state that and provide evidence from the Tipitaka.
There is only one reliable source of Buddha Dhamma, and that is the Tipitaka. That is the sole basis for this website, and therefore, for the discussions at this forum.
P.S. I do understand that “stopping rebirth” or “stopping existence” could be an unsettling thought for many people. That is the ultimate goal, but one who is starting on the Path (even a Sotapanna) should not contemplate on that. One could start at the stage where one does not even believe in rebirth. I have emphasized this point at the “Living Dhamma” section, and many other posts throughout the website.
I also recommend listening to the discourse in, “Three Marks of Existence – English Discourses“.