There’s a step missing in the article to repair the bootloader. In it, you reinstall the kernel but this resets the flags for the packages in the package manager so they’re no longer automatically cleaned up, causing the boot partition to fill up. I’ll reach out to support soon to see what the default settings should be so that I can correct it. 🙂
Eventually, I’ll probably look at seeing if I can help update the steps on their end to include all this information since the docs are open source:)