Samsung Galaxy Note4
The latest firmware for Samsung Galaxy Note4 (SM-N910T2) is N910T2UVU2AOG1 with Android 4.4.4 (Kitkat), released on November 2, 2020 for 1 region (CSC). Every official firmware build for SM-N910T2, newest first: one row per build with all regions (CSC) that received it.
Each firmware build has its own page at https://samfirm.shop/build/{PDA}, where {PDA} is the build number from the list above. Example: https://samfirm.shop/build/N910T2UVU2AOG1
Specifications of SM-N9100, a regional variant of the same device. Chipset and SIM lines are left out: they can differ by region.
· Device stability improvements, bug fixes.
· New and / or enhanced features.
· Further improvements to performance.

SM-N910V

SM-N915V

SM-N916S

SM-N920AZW

SM-N900V
You can find the firmware on the model: SM-N910T2 page.
Yes, all firmware files for SM-N910T2 are 100% official, original, and obtained directly from Samsung servers.
To flash SM-N910T2, you need to download the appropriate firmware, put your device into Download Mode, and use the Odin tool to load the BL, AP, CP, and CSC files.
Downgrading is only possible if the bootloader version (binary bit) of the old firmware matches the current one. Always check the binary version before flashing SM-N910T2.