--text follows this line--
[O] for out (exited) and [I] for in (entered) for Emacs windows focus
events are sent to buffers for the functions registered to the
focus-change-function events, AFAICT, and the frame-focus-state maps to
those codes (t -> [I], nil -> [O]).

In order to reproduce this, one needs to simply do C-u, wait for it to
appear in the mini buffer, and then switch to another frame. The code
"[ O-" will appear in the mini buffer. Upon returning focus to the frame,
the "[ O-" will be replaced by [ I-" in the minibuffer.

This would not be such a problem, if it were not for these codes being
thrown into the _main_ buffer when in LFE major mode ("[O [I [O [I [[O [I
[O]]] I [O [I]]]]]]") and switching back and forth among different Emacs
frames and different system app windows. I communicated to Robert
Virding (the creator and maintainer of LFE mode), but it was unclear to
me if he saw this message. Regardless, I told him that I would seek
assistance from the larger Emacs community on this issue, since it too
occurs in the minibuffer regardless of major modes. It can be replicated
for example in at least both List Interaction ElDoc mode and Text mode.

This behavior of event codes being sent to the minibuffer once C-u is
typed and frames lose focus was first detected in macOS' Terminal app
when connecting to a Raspberry Pi OS instance of Emacs over ssh, then a
local instance of Emacs running in the Terminal app on macOs, and then
finally also replicated on the Windows Console app.

The behavior does not occur when running Emacs in graphical mode.

In GNU Emacs 28.1 (build 1, x86_64-apple-darwin15.6.0, NS appkit-1404.47 Version 10.11.6 (Build 15G22010))
 of 2022-05-11 built on builder10-11.lan
System Description:  Mac OS X 10.11.6

Configured using:
 'configure --with-ns '--enable-locallisppath=/Library/Application
 Support/Emacs/${version}/site-lisp:/Library/Application
 Support/Emacs/site-lisp' --with-modules
 CFLAGS=-DNSTextAlignmentRight=NSRightTextAlignment'

Configured features:
ACL GMP GNUTLS JSON LIBXML2 MODULES NOTIFY KQUEUE NS PDUMPER THREADS
TOOLKIT_SCROLL_BARS ZLIB

Important settings:
  value of $LANG: en_US.UTF-8
  locale-coding-system: utf-8-unix

Major mode: Fundamental