Switching users, then logging back in causes desktop to freeze

After logging back in from switch user, the splash screen appears, but freezes afterwards.

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: sddm 0.18.1-1ubuntu2
ProcVersionSignature: Ubuntu 5.4.0-80.90-generic 5.4.124
Uname: Linux 5.4.0-80-generic x86_64
ApportVersion: 2.20.11-0ubuntu27.18
Architecture: amd64
CasperMD5CheckResult: skip
CurrentDesktop: KDE
Date: Sun Aug 8 15:08:33 2021
InstallationDate: Installed on 2021-08-07 (1 days ago)
InstallationMedia: Kubuntu 20.04.1 LTS "Focal Fossa" - Release amd64 (20200731)
SourcePackage: sddm
UpgradeStatus: No upgrade log present (probably fresh install)
---
ProblemType: Bug
ApportVersion: 2.20.11-0ubuntu27.18
Architecture: amd64
CasperMD5CheckResult: skip
CurrentDesktop: KDE
DistroRelease: Ubuntu 20.04
InstallationDate: Installed on 2021-08-07 (1 days ago)
InstallationMedia: Kubuntu 20.04.1 LTS "Focal Fossa" - Release amd64 (20200731)
Package: plasma-desktop 4:5.18.5-0ubuntu0.1
PackageArchitecture: amd64
ProcVersionSignature: Ubuntu 5.4.0-80.90-generic 5.4.124
Tags: focal
Uname: Linux 5.4.0-80-generic x86_64
UpgradeStatus: No upgrade log present (probably fresh install)
UserGroups: adm cdrom dip lpadmin lxd plugdev sambashare sudo
_MarkForUpload: True