
Samsung Galaxy TabS 10.5
The latest firmware for Samsung Galaxy TabS 10.5 (SM-T807R4) is T807R4TYU1CPJ1 with Android 6.0.1 (KitKat), released on October 5, 2016 for 1 region (CSC). Every official firmware build for SM-T807R4, 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/T807R4TYU1CPJ1
SM-T807R4 started on Android 4 and has received 2 major Android upgrades; it now runs Android 6.0.1 (KitKat). The newest build, T807R4TYU1CPJ1, was released on October 5, 2016. No new build has appeared for 122 months, so regular updates for this model have most likely ended.
Specifications of SM-T807V, a regional variant of the same device. Chipset and SIM lines are left out: they can differ by region.

SM-T807V

SM-T800

SM-T810X

SM-T900X

SM-T818V
The newest firmware for SM-T807R4 runs Android 6.0.1 (KitKat): build T807R4TYU1CPJ1, released on October 5, 2016.
The latest build for SM-T807R4, T807R4TYU1CPJ1, was released on October 5, 2016 (10 years ago).
SM-T807R4 has had no new firmware for 122 months, so regular updates have most likely ended.
Yes, all firmware files for SM-T807R4 are 100% official, original, and obtained directly from Samsung servers.
To flash SM-T807R4, 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-T807R4.