Installer reports over 30 GB of overhead; no TM snapshots or pending macOS updates

[jcm93]

I have tried to thoroughly check my startup volume to see where this reported 30GB of overhead is coming from; DaisyDisk with Full Disk Access permissions reports that I indeed have around 130 GB of free space, conforming roughly with Finder's reports.

I do not have any pending macOS updates, and I have thinned all local Time Machine snapshots with tmutil thinlocalsnapshots / 150000000000 4 (150 GB)

Nevertheless, the Asahi installer reports a pretty inadequate amount of space actually available:

Are there any other known resolutions for this issue?

I have one previous Asahi installation that I removed (and removed all relevant partitions and resized my startup volume to fill the space); this will be my second time partitioning a full volume to install Asahi. Is it at all possible this is some kind of remnant from my old installation?