Why does changing Apple ID resolve Bank Online login problem?

I need help understanding why changing Apple ID resolved inability to login my bank web?
changing my Apple ID is impractical because it create havoc with my previous emails and paid APPs.
Environment
iOS 17.6
Locked or unlocked mode
VPN
Windows Defender

Erasing and reinstalling two iOS devices and login with same Apple ID didn’t help but using different Apple ID is solution.