distorted scans when using 600 dpi grayscale

When scanning at 600 dpi in grayscale, the scanned image is stretched vertically and cut off at the bottom. 600 dpi color, 1200 dpi grayscale, and 300 dpi grayscale do not have this problem. Choosing TIF output instead of PNM output does not alleviate the problem.

This issue occurred only after upgrading from 18.04 LTS to 20.04 LTS.

Distributor ID: Ubuntu
Description: Ubuntu 20.04.1 LTS
Release: 20.04
Codename: focal

xsane:
  Installed: 0.999-8ubuntu2
  Candidate: 0.999-8ubuntu2
  Version table:
 *** 0.999-8ubuntu2 500
        500 http://ca.archive.ubuntu.com/ubuntu focal/universe amd64 Packages
        100 /var/lib/dpkg/status

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: xsane 0.999-8ubuntu2
ProcVersionSignature: Ubuntu 5.4.0-52.57-generic 5.4.65
Uname: Linux 5.4.0-52-generic x86_64
ApportVersion: 2.20.11-0ubuntu27.12
Architecture: amd64
CasperMD5CheckResult: skip
CurrentDesktop: KDE
Date: Thu Nov 12 14:54:37 2020
InstallationDate: Installed on 2019-01-16 (666 days ago)
InstallationMedia: Kubuntu 18.04.1 LTS "Bionic Beaver" - Release amd64 (20180725)
SourcePackage: xsane
UpgradeStatus: Upgraded to focal on 2020-11-09 (3 days ago)