The automatic safeguard also applies to the Pro Display XDR monitor, and when it kicks in, users will see an on-screen warning with an explanation mark in the menu bar. “This can occur if the ambient temperature of the room is high and you've been playing very bright content for an extended period of time,” Apple explains.
How bright is “very bright”? Well, the newest MacBook Pros are capable of displaying 1,600 nits of peak brightness, and up to 1,000 nits of sustained full-screen brightness for HDR content, though SDR seems to be limited to 500 nits (opens in new tab). As such, it doesn’t seem to be a widespread problem, with very few reports online at the time of we published this story.
Nonetheless, if you do find yourself faced with the brightness warning, Apple does have some tips to make it go away.
First, quit any apps that “could be consuming significant system resources” to see if it’s specific software that’s triggering the brightness limit. At the same time, Apple advises you “close or hide any windows with HDR content” and use the screen’s reference mode “unless your current workflow requires a specific reference mode.”
As heat is the trigger of the brightness limiter, Apple also suggests you reduce the ambient temperature of the room — or presumably just move your MacBook Pro somewhere cooler. Finally, Apple advises that if you put your MacBook to sleep for five to ten minutes, it may have cooled sufficiently to restore full brightness.
If these problems persist, and your house isn’t perpetually a 77°F or higher hothouse, Apple advises you to contact support, as it could be indicative of a deeper problem.
The appearance of this support page now is slightly curious timing from Apple. As mentioned, it doesn’t appear to have been triggered by widespread complaints, and while the 2021 MacBook Pro is still quite new, the equally impacted Pro Display XDR has been around for two years now.
Perhaps as we approach the end of winter, Apple is bracing itself for the problem to become more widespread as North American temperatures slowly edge closer to the 77°F danger zone.