Screen freeze at login or after running a graphical session

[Christian Danninger]

After upgrade to Ubuntu 21.04 my laptop Dell Latitude 7480 with Intel graphic card freezes either:
* during entering to boot password (encrypted file system), sometimes
* during entering my password, often
* after my X-session was started, sometimes
When I boot in recovery mode (and resume to normal boot), the problem disappers

ProblemType: Bug
DistroRelease: Ubuntu 21.04
Package: ubuntu-release-upgrader-core 1:21.04.12
ProcVersionSignature: Ubuntu 5.11.0-18.19-generic 5.11.17
Uname: Linux 5.11.0-18-generic x86_64
ApportVersion: 2.20.11-0ubuntu65.1
Architecture: amd64
CasperMD5CheckResult: unknown
CrashDB: ubuntu
CurrentDesktop: ubuntu:GNOME
Date: Thu Jun 10 07:48:22 2021
InstallationDate: Installed on 2020-07-07 (337 days ago)
InstallationMedia: Ubuntu 20.04 LTS "Focal Fossa" - Release amd64 (20200423)
PackageArchitecture: all
SourcePackage: ubuntu-release-upgrader
Symptom: release-upgrade
UpgradeStatus: Upgraded to hirsute on 2021-06-04 (5 days ago)
VarLogDistupgradeTermlog:

[Christian Danninger (cdanning)]

When I start with an older kernel "5.8.0-55-generic" not using the recovery mode, everything looks fine.
Mesa Intel® HD Graphics 620 (KBL GT2)