Just got the T-Mobile Jan 1 Security update on my U device.
Quite happy with the A12 update so far. Although I use Nova Prime and I can't see much under the hood, I like the subtle changes that I'm seeing everywhere else. I like how you can set your battery charge to shut off at 85% which pretty much sadly will put these guys out of business. I also like how you can see your SOT since the last full charge which is something they brought back and should've never gone away to begin with. One thing I don't like as mentioned before is how they got rid of the alphabets in the contact menu and replaced them with dots instead. Boneheaded if you ask me but I'm starting to get used to it... Overall I agree that Samsung has done a great job with its One UI android implementation and improved it greatly to get it to this point.
See Post #2 and #3 for the Links to the Firmware ALL of the firmware posted here can be flashed on any N986U/N986U1 Device. The firmware is NOT carrier dependent and is only listed next to some of them in order to have an idea if you might get OTA when you flash it
Understanding Firmware naming: N986USQU1ATGM
986U or F etc, the model of device
SQ, FX etc = CPU and model specific
U,S,E = Update, Security, Engineering, respectively
1,2,3,4,5 etc = bootloader revision (This is important! You cannot go to a previous revision)
A,B,C,D = Android version
T, U = Year (T=2020, U=2021 etc)
A,B,C etc = month (January A - December L)
1 - 9 and then A - Z =build compilation. This basically means how many builds there are in a month. They start at 1 and go to Z
So N986USQU1ATGM would be
N968U (Note 20 Ultra Carrier version), SQ (Snapdragon), U (Update), 1 (Bootloader version), A (Build 10), T (2020), G (July), M (22nd build)
How to enter Download Mode:
Turn off the device.
Connect USB cable to your PC (Leave it disconnected from the phone)
Press and hold down the Volume Up and Volume Down buttons. While they are still pressed, plug in the USB cable into your phone.
The phone will go into download mode press volume up. In Odin you will see that phone is added.
I would only do this if you are having to manually update to the newer firmware and would not do it if you are coming/going to U/U1 or from beta firmware or if you are on an old firmware. I'd also highly recommend doing a back up prior to the doing this
Load these into Odin
Do NOT flash CSC or USERDATA, either of these WILL wipe your device
This is a "dirty flash" and these can sometimes cause issues. Keep in mind if things start going sideways and stuff starts not working right, your first step to a solution will be to wipe the device.
Tips on flashing U1 Firmware:
You will have to wipe, can NOT dirty Flash going between U and U1 firmware
Use the patched ODIN linked in post #2 or #3, Odin3_v3.13.3b (They are exactly the same)
Have an active US Carrier SIM installed to get carrier features
If you get your CSC Stuck on XAA/XAA/(Insert your carrier here), and can not get Carrier options back.
Go to the tutorial that @borijess put together HERE