Battle.net.exe - Bad Image : C:\Program Files (x86)\Battle.net\Battle.net.14420\Qt5Gui.dll is either not designed to run on Windows or it contains an error. Try installing the program again using the original installation media or contact your system administrator or the software vendor for support. Error status 0xc0e90002.
There is a new security feature in Windows 11 called Smart App Control
This feature if turned on will block all DLL’s that are unsigned and/or DLL’s that are potentially malicious.
I had a quick look at the other DLL’s used as part as the battle.net client and there are many of them that are unsigned.
As this Smart App Control feature becomes more common in usage among Windows desktops it would be wise to update your DLL’s so that they are digitally signed to avoid being blocked.
How Smart control works taken from Microsoft’s support page:
When you try to run an app on Windows, Smart App Control will check to see if our intelligent cloud-powered security service can make a confident prediction about its safety. If the service believes the app to be safe, Smart App Control will let it run. If the app is believed to be malicious or potentially unwanted, then Smart App Control will block it.
If the security service is unable to make a confident prediction about the app, then Smart App Control checks to see if the app has a valid signature. If the app has a valid signature, Smart App Control will let it run. If the app is unsigned, or the signature is invalid, Smart App Control will consider it untrusted and block it for your protection.