The most notorious example I remember was an update to data entry software in the medical field. The old one ran on some Unix iirc, had a text mode interface, and was entirely controlled by keyboard. Staff could use it in their sleep, enter text, tab, enter more text, tab tab, and so on.
The new version ran on Windows, had a lot more features for sure, but suddenly staff was entering data into a field, grabbed the mouse to move to the next field, entered data, and so on. The process became way slower. So I asked why they don't just ignore the mouse and keep using tab. They were surprised this even works, because it was never mentioned by the folks who trained them on the new software. It was all about how modern and slick it looks and how it has so many more features.
So then staff tried to use the tab key again, but got frustrated very quickly since the software was smart enough so enable and disable controls in the entry form depending on selections you made in earlier fields. So tabbing through the form would require different number of key presses all the time, making it hard to build muscle memory. I think they raised their complaints to management but whether that feedback ever reached the software vendor I have no idea. I guess they did get faster again over time because any new system takes time to get used to, but I'd be very surprised if it ever matched the ancient, simple system again.
I would add to that what I call "fractioning" of data (on multiple screens).
We used for years (decades) a DOS based tool, where in a "conventional" 80x25 mask there was enough space for all the data we had to input (navigating with TAB/Enter, etc.) before passing to the next (with F8).
On the new software the same data (in windows, on a modern screen) goes inside a teeny-tiny window that has not enough fields, so it is spread on three tabs and this breaks the flow.
The same happens a lot on forms on the web, fill one or two fields, click next, repeat.
The new version ran on Windows, had a lot more features for sure, but suddenly staff was entering data into a field, grabbed the mouse to move to the next field, entered data, and so on. The process became way slower. So I asked why they don't just ignore the mouse and keep using tab. They were surprised this even works, because it was never mentioned by the folks who trained them on the new software. It was all about how modern and slick it looks and how it has so many more features.
So then staff tried to use the tab key again, but got frustrated very quickly since the software was smart enough so enable and disable controls in the entry form depending on selections you made in earlier fields. So tabbing through the form would require different number of key presses all the time, making it hard to build muscle memory. I think they raised their complaints to management but whether that feedback ever reached the software vendor I have no idea. I guess they did get faster again over time because any new system takes time to get used to, but I'd be very surprised if it ever matched the ancient, simple system again.