Yes I do, it's not that. I always use auto brightness, this is an error happening since the last update. It will go straight dim while the brightness bar is halfway or even higher. It only corrects itself once I touch the slider.
Let's try wiping the cache partition on your device and see if that helps any.
- Turn off the device.
- Press and hold the Volume Up key and the Bixby key, then press and hold the Power key.
- When the Android logo displays, release all three keys.
- An ‘Installing system update’ message will show for 30 – 60 seconds before the Android system recovery menu options appear.
- Press the Volume down key several times to highlight wipe cache partition.
- Press the Power key to select.
- Press the Volume down key to highlight yes, them and press the Power key to select.
- When the wipe cache partition is complete, Reboot system now is highlighted.
- Press the Power key to restart the device.
I would also recommend you testing your device in safe mode to see if you still experience the same symptoms.
Let's try putting the device in Safe mode to determine if there are external factors that cause this symptom. This step will temporarily disable all your third-party apps, but none of your personal data will be deleted. Your customization settings (Wallpaper, Themes, et cetera) will be reset to default once you exit this mode.
Please follow the steps below:
1. Turn the device off.
2. Press and hold the Power key past the model name screen.
3. When "SAMSUNG" appears on the screen, release the Power key.
4. Immediately after releasing the Power key, press and hold the Volume down key.
5. Continue to hold the Volume down key until the device finishes restarting.
6. Safe mode will display in the bottom left corner of the screen.
7. Release the Volume down key when you see Safe Mode.
8. To exit Safe Mode, restart your device.
Let us know how your device responds after performing this step!