Backlight gesture mode issue when running

I am okay with a contradiction and I appreciate what you have added. I do my best to always remain open minded on my understanding of an issue.

It is accurate that the gesture mode feature, which uses your watch accelerometer sensor, can be 'tweaked' for the sensitivity level and it does get adjusted here and there based on reports that we receive on the gesture experience.

Just an observation that might help tracking down the bug:

For me, everything works fine if I keep my backlight duration setting on 8s. Increasing it to 15s causes the bug to appear. It might be a sensitivity issue and 15s ist just long enough to ensure that there is at least one event that causes a gesture, or it might be bug related to the duration setting. 

I keep mine at 4s and the issue still appers. For me it is probably sensitivity issue with the accelerometer, where it is to sensitive for running. The backlight shouldn't turn on, when the arms are swinging from side to side, kept close to the body, but only turned on, when the wrist is turned upward.  

Same here. 4 seconds and regular running motion will trigger the backlight very very often... 

I now called support 3 times asking for help and every time I get the answer that it's by design since running motion looks very much like the gesture..

I'm very upset about this as night running is something I wanted to use this watch for and now I'll have to turn off the gesture setting (which makes it less usable)

I am happy to see it's finally getting some attention though.. hope they address this in a more meaningful way.

Mine has always been set at 4 seconds but will test at 8 tonight and report back. 

I have the same problem on my Forerunner 945 for almost 2 years now. There is a thread on this in 945 forum, people reported it to Garmin (myself included - I even created case on their website and sent collected debug info but never got answer back) and it was never fixed. As a workaround I learned to press light button when I want to see some live run data. Each time there is firmware upgrade I do turn gesture feature back on just to getting it off after several minutes.

Just for funsies, try doing a short run for a few minutes without starting an activity (in regular smartwatch mode) just to see if the backlight behaves as (close to) expected. Make sure the backlight settings are identical for general use and activity. Hint: it probably will. Sure there's a chance you'll see it briefly turn on and off a few times, but most sure it will not stay on. Then draw your own conclusions. 

On fenix 5 this issue was fixed in software v2.72 -> "Fixed a couple of scenarios where the 'In-activity' backlight settings were not being respected."; fenix 5 is currently at v25.00... Maybe that fix could be merged in the fenix 7 branch, or at least take inspiration from it  

Just wanted to chime in that I see this issue on my Fenix 7X as well. I reproduce it reliably within 10-20 steps while making an effort to not turn my wrist.