It's not flashing a custom ROM. It is installing an OS of users choice. Enemy's language shouldn't be used if we want things to change

What makes it "custom"? If you install Linux on a laptop that comes with Windows pre-installed, is Linux then a custom OS it's not being a default? Why phones are any different? Calling it custom you play to the manufacturers pockets making it sound shady and unofficial giving them right to take the control from the customers devices. Soon we won't own anything we buy.

Just uninstall it and download version 2025122009 from aurora store, three dots up right in the app "manual download".

Also blacklist the app to prevent it from updating.

I'm using N26 on GrapheneOS without Google services. Works fine.

The same applies to every pre-installed OS. They are all customized from AOSP, but only third-party operating systems are called such. That was my point there.