
Samsung G9198
The latest firmware for Samsung G9198 (SM-G9198) is G9198ZMS1BQA2 with Android 5.1.1 (Lollipop), released on January 19, 2017 for 1 region (CSC). Every official firmware build for SM-G9198, 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/G9198ZMS1BQA2
All 7 builds in our database run Android 5.1.1 (Lollipop). The newest build, G9198ZMS1BQA2, was released on January 19, 2017. No new build has appeared for 118 months, so regular updates for this model have most likely ended.

SM-G910S

SM-G928A

SM-G900AZ

SM-G925A

SM-G920X
The newest firmware for SM-G9198 runs Android 5.1.1 (Lollipop): build G9198ZMS1BQA2, released on January 19, 2017.
The latest build for SM-G9198, G9198ZMS1BQA2, was released on January 19, 2017 (9 years ago).
SM-G9198 has had no new firmware for 118 months, so regular updates have most likely ended.
Yes, all firmware files for SM-G9198 are 100% official, original, and obtained directly from Samsung servers.
To flash SM-G9198, 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-G9198.