
Samsung Galaxy Mega 2
The latest firmware for Samsung Galaxy Mega 2 (SM-G750H) is G750HXXU1AOE1 with Android 4.4.4 (KitKat), released on June 5, 2015 for 2 regions (CSC). Every official firmware build for SM-G750H, 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/G750HXXU1AOE1
All 2 builds in our database run Android 4.4.4 (KitKat). The newest build, G750HXXU1AOE1, was released on June 5, 2015. No new build has appeared for 138 months, so regular updates for this model have most likely ended.
Specifications of SM-G750, a regional variant of the same device. Chipset and SIM lines are left out: they can differ by region.

SM-G750F

SM-G766U

SM-G850X

SM-G730V

SM-G556B
The newest firmware for SM-G750H runs Android 4.4.4 (KitKat): build G750HXXU1AOE1, released on June 5, 2015.
The latest build for SM-G750H, G750HXXU1AOE1, was released on June 5, 2015 (11 years ago).
SM-G750H has had no new firmware for 138 months, so regular updates have most likely ended.
Yes, all firmware files for SM-G750H are 100% official, original, and obtained directly from Samsung servers.
To flash SM-G750H, 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-G750H.