“app_updater” will damage your computer.

First, start your Mac in "Safe Mode": How to use safe mode on your Mac - Apple Support. Starting in Safe Mode takes longer than usual so let it finish.

While in that mode, drag the following files to the Trash:

Then, restart your Mac normally and confirm the annoying messages cease to appear.

Notes:

• That Mac has at least one VPN installed. I suggest reviewing Don't use VPN services. Despite what some of them may claim VPNs do not protect you from installing malware.
• Like all non-Apple "anti-virus" products "Avira" is garbage. Uninstall it according to its instructions. Neither it nor "Malwarebytes" appear to have prevented you from installing malware, nor do they appear to have helped you remove it. It's up to you whether you want to keep these products installed or not, but if something isn't providing a tangible benefit to you, then it's not worth the effort to keep it.
• "Transcend" may be outdated or was never required to begin with. Same comments apply to it and Teamviewer. If you're not using it, get rid of it.