RasPi OS 32bitをインストールしたのにaarch64??

$ cat /boot/issue.txt
Raspberry Pi reference 2023-05-03

$ uname -m
aarch64
$ uname -a
Linux raspberrypi 6.1.21-v8+ #1642 SMP PREEMPT Mon Apr  3 17:24:16 BST 2023 aarch64 GNU/Linux

$ getconf LONG_BIT
32

$ grep arm_64bit /boot/config.txt
$

$ dmesg | head
[    0.000000] Booting Linux on physical CPU 0x0000000000 [0x410fd083]
[    0.000000] Linux version 6.1.21-v8+ (dom@buildbot) (aarch64-linux-gnu-gcc-8 (Ubuntu/Linaro 8.4.0-3ubuntu1) 8.4.0, GNU ld (GNU Binutils for Ubuntu) 2.34) #1642 SMP PREEMPT Mon Apr  3 17:24:16 BST 2023
[    0.000000] random: crng init done
[    0.000000] Machine model: Raspberry Pi 4 Model B Rev 1.5
[    0.000000] efi: UEFI not found.
[    0.000000] Reserved memory: created CMA memory pool at 0x000000000ec00000, size 512 MiB
[    0.000000] OF: reserved mem: initialized node linux,cma, compatible id shared-dma-pool
[    0.000000] Zone ranges:
[    0.000000]   DMA      [mem 0x0000000000000000-0x000000003fffffff]
[    0.000000]   DMA32    [mem 0x0000000040000000-0x00000000ffffffff]

$ sudo vcdbg log msg
...
005288.622: 'console=serial0,115200 console=tty1 root=PARTUUID=248bdf7b-02 rootfstype=ext4 fsck.repair=yes rootwait quiet splash plym                                                                           outh.ignore-serial-consoles'
005438.117: brfs: File read: 147 bytes
006166.095: brfs: File read: /mfs/sd/kernel8.img
006166.116: Loaded 'kernel8.img' to 0x80000 size 0x7d6bd0

$ cat /boot/issue.txt
Raspberry Pi reference 2023-02-21
Generated using pi-gen, https://github.com/RPi-Distro/pi-gen, f2d385517c9631f2ded876deb1115725d0c75995, stage4
$ uname -m
armv7l
$ uname -a
Linux raspberrypi 5.15.84-v7l+ #1613 SMP Thu Jan 5 12:01:26 GMT 2023 armv7l GNU/Linux
$ getconf LONG_BIT
32
$ grep arm_64bit /boot/config.txt
$ sudo vcdbg log msg
...
006921.796: brfs: File read: /mfs/sd/kernel7l.img
006921.837: Loaded 'kernel7l.img' to 0x8000 size 0x6b9738
...
$ dmesg | head
[    0.000000] Booting Linux on physical CPU 0x0
[    0.000000] Linux version 5.15.84-v7l+ (dom@buildbot) (arm-linux-gnueabihf-gcc-8 (Ubuntu/Linaro 8.4.0-3ubuntu1) 8.4.0, GNU ld (GNU Binutils for Ubuntu) 2.34) #1613 SMP Thu Jan 5 12:01:26 GMT 2023
[    0.000000] CPU: ARMv7 Processor [410fd083] revision 3 (ARMv7), cr=30c5383d
[    0.000000] CPU: div instructions available: patching division code
[    0.000000] CPU: PIPT / VIPT nonaliasing data cache, PIPT instruction cache
[    0.000000] OF: fdt: Machine model: Raspberry Pi 4 Model B Rev 1.5
[    0.000000] random: crng init done
[    0.000000] Memory policy: Data cache writealloc
[    0.000000] Reserved memory: created CMA memory pool at 0x000000001ac00000, size 320 MiB
[    0.000000] OF: reserved mem: initialized node linux,cma, compatible id shared-dma-pool