I got a reply from someone that it takes the distance from home to decide on trigger
This is in reference to the "Smart RTH" feature in DJI GO
(in the "Main Controller Settings" --> "Advanced Settings" section). If that setting is enabled, your Phantom will display a prompt and auto RTH in 10 seconds when the current battery level meets the "H" marker in DJI GO. The "H" will slide to the right as you fly further away from the home point -- since it'll take longer for your Phantom to return to the home point. If your Phantom is close to the home point, it would not be unreasonable to see the "H" marker around the 15% battery level.
Your log is showing the critical low battery level
(the 10% you set) and the current "H" location
(rather than the low battery setting). At the beginning of your logs, the "H" is always at 15% -- which is why I was noting it's set to 15%. As I scrolled down through your log, that number was increasing
(as the "H" moved on the meter). So, your log is not showing the low battery level as I had indicated above.
To sum up, all is working as expected. Your Phantom should not auto RTH when it reaches the 30% low battery level. It should only auto RTH if you're using the Smart RTH feature and the current battery level is at the "H".
FYI, in your last log above, your Phantom started to auto land because it was within 20m of the home point.