Partition layout of ARM SD card images

For example let's have a llok on the partition layout of, FreeBSD-13.1-RELEASE-arm64-aarch64-RPI.img (the others are similar):

# mdconfig -a -u 0 -t vnode -f diskimg/FreeBSD-13.1-RELEASE-arm64-aarch64-RPI.img
# gpart show md0 md0s2

   =>     63  6291393  md0  MBR  (3.0G)
          63     2016       - free -  (1.0M)
        2079   102312    1  fat32lba  [active]  (50M)
      104391  6187041    2  freebsd  (3.0G)
     6291432       24       - free -  (12K)

   =>      0  6187041  md0s2  BSD  (3.0G)
           0       57         - free -  (29K)
          57  6186880      1  freebsd-ufs  (2.9G)
     6186937      104         - free -  (52K)

The start of the fat32 boot slice s1 (containing the u-boot) stuff is neither aligned to 1M nor to 4k, it starts on an odd base. The start of the BSD payload slice s2 and its size are odd as well. The padding of 57 blocks within s2 lets the UFS partition start on a globally even base, namely 104391+57 = 104448, which as a matter of fact is 4k aligned (104448*512/4096 = 13056) and 1M aligned as well (104448*512/1024/1024 = 51), however all this keeps looking strange.

Are there reasons for this partition layout besides making it look more interesting? If yes, some insights would be good.

For the time being, I created a second SD card from the initial one for my RPi 4, and it's partition table is as follows:
 
# gpart show mmcsd0 mmcsd0s2
   =>      63  62410689  mmcsd0  MBR  (30G)
           63        25          - free -  (13K)
           88    102312       1  fat32lba  [active]  (50M)
       102400  62308352       2  freebsd  (30G)

   =>       0  62308352  mmcsd0s2  BSD  (30G)
            0  56623104         1  freebsd-ufs  (27G)
     56623104   5685248         2  freebsd-swap  (2.7G)