Lightdm not working since system updates 2021-06-15

[AO]

On Ubuntu Impish.
Since the system was updated 2021-06-15, Lightdm is not working anymore, the system loads to a black screen with a cursor.
Gdm3 does work.
Reproducible on two separate computers

ProblemType: Bug
DistroRelease: Ubuntu 21.10
Package: lightdm 1.30.0-0ubuntu4
ProcVersionSignature: Ubuntu 5.11.0-20.21+21.10.1-generic 5.11.21
Uname: Linux 5.11.0-20-generic x86_64
ApportVersion: 2.20.11-0ubuntu67
Architecture: amd64
CasperMD5CheckResult: unknown
CurrentDesktop: Unity:Unity7:ubuntu
Date: Sat Jun 26 09:59:15 2021
InstallationDate: Installed on 2020-03-15 (467 days ago)
InstallationMedia: Ubuntu 20.04 LTS "Focal Fossa" - Alpha amd64 (20200106)
SourcePackage: lightdm
UpgradeStatus: No upgrade log present (probably fresh install)
modified.conffile..etc.default.apport: [modified]
mtime.conffile..etc.default.apport: 2020-03-15T11:56:34.801446