The philosophical self

Hello Michi
I am already clearing the psychological self/ego and other psychological descriptions.
What is this philosophical "I" that exists as an object in the spiritual world? Various psychedelic drugs (mushrooms, ayahuasca, etc.) cause a person to disconnect from themselves. Brain scans show a cessation of blood flow to a certain area (called the default zone, where memories and the sense of self are located, among other things) and the person experiences a kind of mystical event in which he does not feel himself at all, but as part of a greater whole (this is described as "in absolute love" or "with God"). If this is so, then the "I" is experienced only when it is connected to a certain area of ​​the brain, and if not, then it is no longer experienced. It is important to note that when a person is in a psychedelic trip, he does not feel himself *at all*, and the feeling is that everything is one and there are no separations. If so, does the "I" really exist? What is this I without thought, choice, conscience, intuition in general, and the sense of self?
If the self exists, then how would you explain what happens within the psychedelic experience? Is the self "inside" the experience? Or maybe it's not there and the person disconnects from their self for a certain period of time?
I hope my questions are clear, and if not I will clarify what is needed.