Application launcher flashes

When starting some application from the application launcher - e.g. the keyboard setting utility, the application launcher keeps flashing when I am using the started application. The flashing disappears when I close the application.

It seems that this happens to some applications and not all.

I have uploaded a video showing the issue:

https://youtu.be/OtxD9aFE2-E

I am running Ubuntu in Parallels (latest) on a Macbook Pro.

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: plasma-workspace 4:5.18.5-0ubuntu0.1
ProcVersionSignature: Ubuntu 5.11.0-41.45~20.04.1-generic 5.11.22
Uname: Linux 5.11.0-41-generic x86_64
NonfreeKernelModules: prl_fs_freeze prl_fs prl_eth prl_tg
ApportVersion: 2.20.11-0ubuntu27.21
Architecture: amd64
CasperMD5CheckResult: skip
CurrentDesktop: KDE
Date: Wed Dec 15 13:37:24 2021
ExecutablePath: /usr/bin/plasmashell
InstallationDate: Installed on 2020-10-27 (414 days ago)
InstallationMedia: Ubuntu 20.04.1 LTS "Focal Fossa" - Release amd64 (20200731)
SourcePackage: plasma-workspace
UpgradeStatus: No upgrade log present (probably fresh install)