This happens to me when I travel to Japan for work (I think about 40% basal reduction), but in my case I would dispute that my diet and exercise remain the same. As far as exercise, I am just much more active in Japan. At home I drive to my parking lot and walk in the door; same at night; the only real exercise I get is when I go to the gym. In Japan I walk to and from the train station, stand in the train, walk to restaurants for lunch and dinner, walk to see sights in my time off, etc.
I am also eating a Japanese diet, which is higher in carb and lower in protein and fat. But it is also smaller serving size than in the US. So although I am eating a higher percentage of carb in Japan, my total calorie intake is somewhat less. And this, combined with the additional exercise, is what I believe is responsible for the lower basal I need when in Japan.
The last time I was there it was for almost four weeks, and these results were consistent. And I lost weight while I was there, lending support to the conclusion about changes in exercise and lower calorie intake. In your case, how long do you stay? If more than a few days it must be something similar (otherwise you would quickly acclimatize and insulin would return to normal).
(I just noticed you’re a recent-onset LADA, so you’re probably still producing a lot of your own insulin - so maybe it’s different for you. In my case I’ve had T1 for 39 years).