People still have trouble with unpredictable behavior of 'C-x 0'
that selects an unexpected window after the current window is deleted.

This is a recent example:
https://old.reddit.com/r/emacs/comments/m8omt0/how_can_deletewindow_cx_0_be_configured_to_stay/

The previous failed attempt to fix this was in bug#32790.

I still don't understand the current logic what window is selected
after deleting the selected window with 'C-x 0'.

But maybe this could be customizable?  Tried to write an advice:

(advice-add 'delete-window :around
            (lambda (orig-fun &optional window)
              (if window
                  ;; Non-interactive call
                  (funcall orig-fun window)
                ;; Interactive call
                (let* ((pos (window-absolute-pixel-position))
                       (x (when pos (/ (car pos) (frame-char-width))))
                       (y (when pos (/ (cdr pos) (frame-char-height)))))
                  (funcall orig-fun window)
                  ;; Select window that takes space from the deleted window
                  (when (and x y)
                    (select-window (window-at x y))))))
            '((name . delete-window-keep-pos)))

Maybe something like this could be adapted to delete-window
by adding an optional interactive argument keep-pos: