the „my day“ widget shows the intensity minutes from the whole week.
It should only show the intensity minutes from the actual day, like it does on my
Fenix 3hr.
I can't find the reference otherwise I'd post it, but I am sure I've seen confirmation that although it's the My Day widget the intensity minutes are still weekly. I.e. It's not a bug
I don't know if your fenix f3hr is different from mine or what, but it has always shown weekly accumulated activity minutes, it's part of the reason why when I upgraded to the 5X I didn't choose activity minutes or steps as widgets since they are both included in the my day widget.
There is an Intensity Minutes widget that you can add to your list of widgets that does show the same daily intensity minutes that you saw on your fenix 3 HR. This intensity minutes widget is one that isn't enabled by default, but if you go to Widgets under settings and then Add Widgets, you can find intensity minutes. You have to hit Start then Down once you get the widget showing on the watch.