Brightness jumping on secondary display when different participants speak

Hi Zoom Community,

I'm experiencing a display brightness dimming issue on my secondary monitor that has been present since at least Zoom version 6.5. I'm reporting this in hopes that the Zoom team can investigate and address it in an upcoming release. 

**Setup:**
- Lenovo ThinkPad T40s, Windows 11
- Zoom Workplace with Dual Display mode enabled
- Secondary display output via HDMI to an AJA KiPro Go (external recorder)
- Laptop configured to extend display at 60hz
- Secondary window from Zoom full-screened onto the secondary display
- Multiple participants in meeting with Participant 1 pinned to the secondary display

**The Issue:**
When Participant 1 (the pinned participant) is speaking, the secondary display looks correct. However, when any other participant speaks and the gallery view highlights them, the secondary display visibly dims. When Participant 1 speaks again the display brightness returns to normal. This dimming is visible both on the physical secondary display and in the recorded output from the KiPro Go, confirming the HDMI signal itself is being affected.

**Troubleshooting steps already completed — none of which resolved the issue on Zoom 6.5 or 6.7:**

- Disabled Content Adaptive Brightness in Windows Settings (System > Display > Brightness > Change brightness based on content > Off)
- Disabled Intel Display Power Saving Technology (DPST) in Intel Graphics Command Center > System > Power, for both On Battery and Plugged In profiles
- Disabled Adaptive Brightness in Control Panel > Power Options > Advanced Settings > Display
- Disabled Variable Refresh Rate in Settings > System > Display > Advanced Display
- Disabled Ambient Light Sensor in Device Manager
- Disabled Dynamic Lock and presence-sensing features in Windows Sign-in Settings
- Disabled Human Presence Detection in Lenovo Vantage
- Changed Zoom Video Rendering Method to Direct3D11 in Settings > Video > Advanced
- Created a system restore point and tested each setting in isolation to rule out compounding variables

**The only thing that has resolved the issue:**
After visiting Zoom's archive page and testing previous versions, 5.17.5 is the only version where the dimming does not occur with the exact same hardware and Windows configuration.

This strongly suggests the issue was introduced somewhere between version 5.17.5 and 6.5. Given that 5.17.5 is approaching end-of-life, this is becoming an urgent issue for our recording workflow.

Has anyone else experienced this? Is there a known fix or a specific version where this was introduced? Any help or acknowledgment from the Zoom team would be greatly appreciated.