For several decades, I have used hundreds of different computers, from IBM mainframes, DEC minicomputers and early PCs with Intel 8080 or Motorola MC6800 until the latest computers with AMD Zen 5 or Intel Arrow Lake. I have used a variety of operating systems and user interfaces.
During the first decades, there has been a continuous and obvious improvement in user interfaces, so I never had any hesitation to switch to a new program with a completely different user interface for the same application, even every year or every few months, whenever such a change resulted in better results and productivity.
Nevertheless, an optimum seems to have been reached around 20 years ago, and since then more often than not I see only worse interfaces that make harder to do what was simpler previously, so there is no incentive for an "upgrade".
Therefore I indeed customize my GUIs in Linux to a mode that resembles much more older Windows or MacOS than their recent versions and which prioritizes instant responses and minimum distractions over the coolest look.
In the rare occasions when I find a program that does something in a better way than what I am using, I still switch immediately to it, no matter how different it may be in comparison with what I am familiar, so conservatism has nothing to do with preferring the older GUIs.
“I've come up with a set of rules that describe our reactions to technologies:
1. Anything that is in the world when you’re born is normal and ordinary and is just a natural part of the way the world works.
2. Anything that's invented between when you’re fifteen and thirty-five is new and exciting and revolutionary and you can probably get a career in it.
3. Anything invented after you're thirty-five is against the natural order of things.”
Douglas Adams
How exactly are you doing that? with 3D Secure online credit card transactions now require confirmation in the mobile app (or via OTP sent by SMS, but this is being phased out, as it is insecure)