True battery life is ... 2 days?

After some back & forth with Support and frustration over somewhat less reliable info from my Venu 3 since the last couple of updates... I discovered that enabling Auto activity start took care of some of the problem.  However, as a direct result my==thebattery life for my 7 month old watch went from about 8 days to less than 2 days.

What I don't get is why the last 2 updates had rendered a great deal of the data trickling down through the Connect app as unreliable. This I am basing upon use of the Venu 3 and an Oura 3 in parallel as well as subjective experience.

Does the firmware now progressively "kneecap" data reporting frequency in order to preserve perceived battery life? I have the distinct impression that the watch I purchased is not "the same" since the last 2 updates.