update-initramfs and no space left on device.

Ah the joy of patch-Tuesday. Or patch-Thursday in my case. So assorted Windows machines updated I thought I'd better check some Linux machines. The other week a colleague texted me and pointed out a nasty SSH regression being exploited. So I sat in Lyon Airport waiting for the gate to be announced and updated my Pi ZeroW gateway and some VMs. I just did the SSH updates. It's cool being able to control your machines from a distance but using the laptop and a phone with roaming data is asking for something to take you offline when you don't want. Today was time to catch up with other updates....
All was fine apart from the Pi Zero W which gave an error when running update-initramfs claiming there was no space on the device when doing
"update-initramfs: Generating /boot/initrd.img-6.6.31+rpt-rpi-v7l"
There was plenty of space on the device so I tried again. No luck. Various ideas tried but it failed at the same place every time. I pulled out another SDcard, wrote the image to it, put in the Pi, booted and then did an update and upgrade. It failed again at the same place. So it wasn't the SDcard that was misbehaving. I flailed about miserably wondering what it was till I found this webpage.
https://hillenius.net/post/nospaceleft/
I followed that and sure enough, it fixed everything. What I don't yet understand is what I had done to get to this place. And if it's just started for me, are other people going to find themselves in the same situation real soon now?
I run '2024-03-15-raspios-bookworm-armhf-lite.img' with a few tweaks to place logs etc. on the ram disk and I've been running apt update etc. on that since end of May. Whatever, after today's update it was not going to work unless I followed those changes to initramfs-tools.
Hopefully this may help the next Pi user who gets bitten by this.