Flying the Mavic 3T and I keep getting low battery voltage warning. The battery percentage is fine but I get a low voltage warning starting under 15.0 V even though the battery percentage is still near 50%. On the safe side, I've been landing but I'm getting concerned. This is happening on multiple batteries and flying both regular flights and autonomous through Flighthub 2. Drone, remote and batteries all updated.

Voltage irregularities should have nothing to do with the battery percentage.  It sounds like something is off with your drone if multiple batteries are doing the same thing.  I would get DJI to replace that one ASAP.

Were the batteries cold when you got this warning,  usually you would also get a battery temp warning when you first boot up.   M right be worth posting a log - http://phantomhelp.com/logviewer/

I havn't try on M3T but on M300 there are specific settings for each battery, especially for self-discharge. But you can also adjust the low level. Take a look in the application, look at the voltage of each element, it must be the same everywhere, +/- 0.1V. There are 4 elements per battery.Try to manage to land the drone never below 14.85V every time. It's just over 3.7V per cell which is the rated voltage of a lithium polymer cell. Lower is bad for the battery, so call deep-discharge. 3.4V per cell is the point where you may destroy the battery. When it's cold, the voltage will degrade very quickly and exponentially. So if you set the auto-RTH at 20% there shouldn't be any problem. The drone will manage the RTH for you depending on the distance.  

When DJI write 45min max flight in the spec they should add "by destroying the battery". Instead of that, they mention below :

[4] Measured with Mavic 3 Enterprise Series flying at a constant speed of 32.4 kph in a windless environment at sea level until the battery reached 0%. Data is for reference only. Please pay attention to RTH reminders in the DJI Pilot 2 app during flight.
They are funny at DJI. Marketing with option I'm not lying but I'm not telling the whole truth.

Otherwise you return your batteries to the after-sales service by creating a ticket on the support. It's fast, they won't ask any questions.

Hi there, sorry for the issue you encountered. May I know the environment temperature while flying? Please try to charge the battery to full and discharge the battery and check again. Please keep us updated if the error persists.

My fault and thanks for the advice everyone. I guess I accidentally changed the "Customize Battery Warning" which caused the confusion. Changed it back and all is good!!!

My fault and thanks for the advice everyone. I guess I accidentally changed the "Customize Battery Warning" which caused the confusion. Changed it back and all is good!!!