Hello, mates! It's been a long time! 
I'm back after a long time, after suffering a "problem" with my Forerunner 955 Solar and reaching a conclusion that, I think, can help people on the forum :)
As you already know, one of the things I liked and valued most about my Forerunner 955 Solar was the battery life. We talked during some time about battery life, autonomy, and more in this thread.
Unfortunately, a few months ago, the autonomy dropped drastically and I started to suffer a huge battery drain without any reason.
What had before? After many years, I upgraded my phone from a Xiaomi Mix 2S to a Pixel 9.
As I commented in the previous thread several times, if I don't go out for running, my Forerunner 955 Solar consumes only a little more than 4% of battery per day. That's 22-23 days of battery life -which makes me very happy-.
But, here comes the issue, since I switched to the Pixel 9 last November I've had a concerning battery drain. Days where the consumption, without doing any activity, was 6, 7, or even 8%. Horrible, really bad autonomy. Sometimes the Forerunner didn't even last two weeks.
What is the first thing I think of? Well, the obvious: the new smartphone -Pixel 9- is causing this, and it must be mainly the communication between mobile phone and watch, that is to say: Bluetooth and permissions.
I tried everything: linking and synchronizing both devices using the Garmin Connect interface. Nothing, sometimes 8% consumption without doing anything in a day!.
Also, I tried to link and synchronize both devices with the Android BT options, and the same thing: sometimes it seems to be relatively fine, but the consumption is still abnoramlly high.
I give up and even get angry because, if it is battery degradation, I think it is too soon for a watch with only 2 years of use.
And suddenly, after almost 4 months, it occurs to me to think and try something.
I don't like the new design of Garmin Connect at ALL, and when using my old smartphone I decided not to update the app anymore to keep the old design. Ok, all was perfect: 4% consumption per day on my old Mix 2s.
What did I do when I switched to Pixel 9? Download an old, but random, version of Garmin Connect to avoid the new tile-based design. Concretely, GC 4.77.1
And here comes the conclusion: that particular version of Garmin Connect was causing a MASSIVE battery drain on my watch for months! I disable background use of the app, I close it after checking data... but nothing... now I know that that specific version of the app was causing the battery drain.
5 days ago I updated to the latest version of Garmin Connect and, indeed, after this time (without doing sport due to a small operation I had, so I've been able to test this now better than before), I'm, currently, still with 79% battery. That's slightly above 4% of consumption per day.
From this, we can deduce that a particular version of Garmin Connect can cause a big difference in the consumption of the watch.
Why? I don't know. I work in IT and I can guess that it may be an internal code problem, a more aggressive communication configuration between the watch and the mobile, or whatever.
The thing is that, if you are suffering battery drain, apart from the multiple reasons that can exist for it, try also temporarily to change the GC version, and wait a few days.
In my case, after trying and testing a lot of options, it was "just" that. Not a smartphone problem, not a Forerunner problem, not a BT problem, not a background permissions problem...
What I'll do is boot up my old phone again, and see exactly which version of the app with the previous UI I was using that didn't cause this leak.
Hope this helps someone!
Best regards to all!
