Just now, !5000 was merged which brings many great improvements! However, it also results in the postmarketOS boot image growing, which due an unfortunate coincidence with a bug in boot-deploy, may result in partial boot images being flashed to the boot image partition on devices with particularly small boot image partitions.
If your device is affected by this, on system upgrade, you may get output similar to this:
== Using boot-deploy to finalize/install files ==
==> Running hooks
==> kernel: device-tree blob operations
==> kernel: appending device-tree exynos4412-p4note-n8010
==> initramfs: creating boot.img
==> Checking free space at /boot
... OK!
==> Installing: /boot/initramfs
==> Installing: /boot/initramfs-extra
==> Installing: /boot/exynos4412-p4note-n8010.dtb
==> Installing: /boot/boot.img
==> Flashing boot image
Flashing boot.img to 'BOOT'
dd: error writing '/dev/mmcblk0p5': No space left on device
9+0 records in
8+0 records out
8388608 bytes (8.0MB) copied, 0.062911 seconds, 127.2MB/s
22:48:05.607882 boot-deploy completed in: 5.12s
In that case, you can (and should, as otherwise the device may no longer boot) fix it by running $ sudo apk add postmarketos-initramfs-minimal, and then $ sudo apk fix to get rid of the error.
If you feel like it, you can also either open an issue about your device being affected (along with logs, ideally), or go the extra mile and submit a merge request fixing the issue! To do so, you would find your device's device package in the pmaports git repository, and add postmarketos-initramfs-minimal to depends, and then increment pkgrel by 1 (so, if it for example was 3, you should increase it to 4).