At least in Spain we have multiple ways of batter-fry our food, which are simply different and not "wrong" per se. For example with calamari you can have them "calamares rebozados"[1] vs "calamares a la romana"[2], which are two very different styles of doing it. And then even within those there are variations ofc. While Japanese Tempura is very homogeneous on its style all across, like most of Japanese food (quality might vary a lot, but cooking styles usually don't).

Then there is the point of oil, while we'd normally use olive oil in Spain, it's crazy expensive in Japan so surely they use other oils, which also change the taste and very likely make it feel lighter.

[1] https://content-cocina.lecturas.com/medio/2021/06/09/calamar...

[2] https://cdn3.misrecetascaseras.com/sites/default/files/style...