They do this for MBP market segmentation now, but really, this started with the ProDisplay XDR.
At the time, people wondered about how they were able to drive the 6K 10 bit display, as the math didn't fit the spec.
People like me found out. Because they completely fucked with DP1.4 specs to make it happen with Big Sur.
In Catalina, my Intel Mac Pro happily drove 2 4K HDR monitors at 144 Hz. Upgrade to Big Sur, not any more. 95Hz for 4K SDR, 60Hz for 4K HDR. Not the cables, not the monitors. Indeed, "downgrading" the monitors advertised support to DP 1.2 gave better options, 120Hz SDR, 75Hz HDR.
Hundreds of reports, different card/cable/monitor combos.
Was at least still the case as of Ventura, which makes sense, because it wasn't a bug, it was just an Apple style fuck you to anyone not fully invested in "all Apple, all the time".
They do this for MBP market segmentation now, but really, this started with the ProDisplay XDR.
At the time, people wondered about how they were able to drive the 6K 10 bit display, as the math didn't fit the spec.
People like me found out. Because they completely fucked with DP1.4 specs to make it happen with Big Sur.
In Catalina, my Intel Mac Pro happily drove 2 4K HDR monitors at 144 Hz. Upgrade to Big Sur, not any more. 95Hz for 4K SDR, 60Hz for 4K HDR. Not the cables, not the monitors. Indeed, "downgrading" the monitors advertised support to DP 1.2 gave better options, 120Hz SDR, 75Hz HDR.
Hundreds of reports, different card/cable/monitor combos.
Was at least still the case as of Ventura, which makes sense, because it wasn't a bug, it was just an Apple style fuck you to anyone not fully invested in "all Apple, all the time".
https://news.ycombinator.com/item?id=25437219