Incorrect heart rate walking uphill, frequent sustained loss of Bluetooth connection & high battery consumption

I have owned my first Vivoactive 4 (VA4) since November 2019 but despite several updates to the device there are some issues that are annoying to a point where I am wondering if this the right device for me?

Incorrect heart rate walking uphill

I don't know why, but the heart rate measured by the VA4 is way off when I walked uphill on an ~10 % incline for 340 meters using the Walk activity. Despite my heart pumping, according to my VA4, I had a maximum hear rate of 137. However, during my 2 kilometer walk with an incline of ~2 % to the starting point I reached a maximum heart rate of 144. Why does my VA4 calculates my heart rate decreasing when the incline quintupled whilst my heart pumped to the point where I had to stop and measured around 170 BPM when checking my pulse on my carotid artery? I actually ended the activity when I reached the top and started a new Walk activity to see if the previous activity was buggy. Turned out though that I experienced the same issue again.

Now, of course one could argue "Use the Garmin chest heart rate monitor", but why? If the wrist heart rate monitor inside the VA4 works with high accuracy during walking and running on level surface, why should it not work when I am walking uphill on an 10 % incline? A colleague of mine also has a VA4 and the exact same issue with inclines and heart rate accuracy.

Frequent sustained loss of Bluetooth connection

If the VA4 synchronizes/updates it can take a while, and I am fine with that. What is not great though is that for several random days within a given week my VA4 does not connect to my iPhone 11 Pro at all for hours. I usually find this out when I try to clear a notification of my VA4 and get an error exclamation mark indicating there is no connection to my phone. This has already resulted in not being notified when a message was received or when a phone call was incoming. However, on other days though it connects flawlessly and notifications work fine. I performed a factory reset of the VA4 with no effect on this. The only things that seems to fix this is to manually go into the Bluetooth settings on my iPhone and select my VA4 in the menu so that it manually connects to it. When I then go back into the Garmin Connect app it suddenly synchronizes data for up to 2 minutes at a time and I see large changes in data such as steps, stress level, calories etc. Due to this large change it indicates to me that the data was not synchronized for hours. It used to connect to the same iPhone a lot better when I purchased the VA4, but over the last 3 months it appears to have more and more "phases" where it just does not want to synchronize/connect for some reason.

What is the point of having a notification feature if the Bluetooth drops out and doesn't connect at all for hours on end?

High battery consumption

I am sure this can be a controversial topic as consumption of the VA4's battery depends on many factors like the watch face used, GPS usage, additional satellite system to GPS, brightness, Pulse Ox enabled etc. However, I find that over the last couple of months I am getting less battery life out of my VA4 compared to when I bought it in November 2019 despite having made the following changes in an attempt to extend my time before a recharge is required:

Summary: In November 2019 I used to get 2.5 days of battery life (40 % / day) which improved to about 4.5 to 5 days (20 - 21 % / day) when I changed Pulse Ox enabled all the time to Pulse Ox only enabled during sleep. As of July 2020 I am getting about 3.5 to 4 days of battery life (23 - 27 %) despite having lowered/changed settings that, in my opinion, should have an effect on battery usage compared to what settings I had previously.

I am open for suggestions about what to do about these issues, thank you.