High temperatures may lower brightness on Pro Display XDR or 2021 MacBook Pro
Apple has a new support document detailing how high temperatures can limit the brightness on the 14-inch MacBook Pro with Liquid Retina XDR display or the Pro Display XDR.
By Cookie Monster -
The Apple 14-inch MacBook Pro.
If you're using the 14-inch MacBook Pro with Liquid Retina XDR display or the Apple Pro Display XDR, be mindful of the ambient temperature of the room or playing of very bright content on the device.
Apple's new support document states that a warning symbol may appear in the menu bar or Display menu in Control Center when the screen is running too hot. This could be due to the high ambient temperature of the room or that you've been playing very bright content for a long period of time. The display will automatically be placed in low power mode with limited brightness.
You are advised to quit any apps that consume significant system resources, or lower the ambient temperature of the room. You can also close or hide any windows with HDR content, and put the Mac to sleep so that the display can cool down for 5 - 10 minutes.
If the issue still persists and the ambient room temperature is below 25 degrees celsius, you have to contact Apple for assistance.