When I updated (Pure Store) some days ago, it was only Millipixels (or Lollypop?).
It failed, saying no space on /boot. I scratched my head why boot would even be touched.
But I solved it with “apt autoremove” which removed the 5.13 kernel, leaving 5.15 and 5.16.
I assume it’s on purpose that a backup kernel stays installed, but the autoremove should be automatic when using the UI for updates.
I now have 105MB available. Wondering whether I should remove one more kernel before the next update.