He did; he said he was running EE.
Boot environments certainly could be part of it, but are unlikely to be all of it. You have something going on on your system that’s saving data to the boot device, most likely either in /root or /home/admin. Looking in those directories will likely find what’s that data is, and then you can move it to your pool.
I don’t think this is so much the case any more, but in the past, the most common culprit I’d see was FTP–one of its defaults was storing data in /root. You may want to check that out.