This isn’t a “myth” they detect both root & custom ROMs so even if you wanted to use an unrooted custom ROM you can’t. Rooting your phone just to skirt around them should be the opposite of what they want as there is some security implications to rooting your phone. And the current solutions are all temporary workarounds til the banking apps find a new way to partner with Google to prevent modifications of any kind.
In my country, at least one bank has shutdown & discontinued their website which is often just the first domino before others start doing it too. My bank is slow to adopt tech, but their site was created to detect IE and Netscape Navigator. I would assume they would kill that website before upgrading it to actually work on the modern web where a fixed CRT isn’t the only screen size.