It looks like /etc/armbian-image-release shows information from the originally installed image and /etc/armbian-release shows information from current/running version:
I originally flashed "Armbian_21.08.3_Bananapipro_buster_current_5.10.60.img" on my Banana Pi Pro so my outputs look like this:
pi@bananapipro:~$ cat /etc/armbian-image-release
# PLEASE DO NOT EDIT THIS FILE
BOARD=bananapipro
BOARD_NAME="Banana Pi Pro"
BOARDFAMILY=sun7i
BUILD_REPOSITORY_URL=https://github.com/armbian/build
BUILD_REPOSITORY_COMMIT=bc7dfd1dd-dirty
DISTRIBUTION_CODENAME=buster
DISTRIBUTION_STATUS=supported
VERSION=21.08.3
LINUXFAMILY=sunxi
ARCH=arm
IMAGE_TYPE=stable
BOARD_TYPE=conf
INITRD_ARCH=arm
KERNEL_IMAGE_TYPE=Image
IMAGE_UUID=ed469859-95ae-4de6-a728-16ae30cf6eda
pi@bananapipro:~$ cat /etc/armbian-release
# PLEASE DO NOT EDIT THIS FILE
BOARD=bananapipro
BOARD_NAME="Banana Pi Pro"
BOARDFAMILY=sun7i
BUILD_REPOSITORY_URL=https://github.com/armbian/build
BUILD_REPOSITORY_COMMIT=92a1c729d-dirty
VERSION=22.02.1
LINUXFAMILY=sunxi
ARCH=arm
IMAGE_TYPE=stable
BOARD_TYPE=conf
INITRD_ARCH=arm
KERNEL_IMAGE_TYPE=Image
BRANCH=current
pi@bananapipro:~$
> "IMAGE_TYPE changed to user-built from stable."
Guess your installation (buster on nanopi-r4s) was put to csc status. Check status of buster in /etc/armbian-distribution-status.
Edit:
According to https://github.com/armbian/build/blob/master/config/targets.conf only bullseye and focal are officially supported on nanopi-r4s now.
