Smooth scaling toggle does not enable on Macbook Neo

[JuanpaG94]

What happened

Description

When using Crisp with a MacBook Neo(A18 Pro + MacOS 27 Golden Gate) connected to an external Philips PHL 278E1 monitor, the smooth scaling toggle does not work, the system asks for the password, it enables the accesibility permission, the screen flashes, but it does nothing. When screen gets back to normal from the black flash, the toggle is still disabled and I cannot use smooth scaling.

My Philips 278E1 monitor is 4K and supports HiDPI in 1440p with looks like 1440p2x, and I have it fully working natively in another device (A MacBook Pro with M1 Pro chip)

I don't know why I cannot make it to work on my MacBook Neo (A18 Pro chip), which only works with 1080p HiDPI natively, and doesn't let to choose other options

Actual behaviour

The toggle does not respond, and the setting does not change.
External monitor goes black after activation attempt(presumably to restart and try to apply the setting), but when the external monitor recovers, the toggle it's not enabled.
No errors are thrown on screen. It simply does nothing.

Steps to reproduce

Connect a MacBook Neo (A18 Pro) to an external monitor.
Open Crisp from menu bar
Click on external monitor settings (Philips PHL 278E1 in this case)
Click on smooth scaling activation toggle
The toggle does nothing and cannot enable, no error is thrown

Crisp version

1.6.0

macOS version

macOS 27.0 Golden Gate

Mac model and chip

MacBook Neo (A18 Pro)

Monitor(s) and how they are connected

Philips PHL 278E1
USB-C to DisplayPort cable

Anything else

Please tell me if I need to send you some logs and how can I do it.
Thank you in advance, and thank you for your support and hard work on this app

Crisp log

No response

[didriksg]

Thank you for posting! This is most likely caused by the Neo's chip, not your monitor or your setup. On an M-series Mac, "looks like 2560x1440" on a 4K monitor is drawn at 5120x2880 and then scaled down to fit the panel. That is why it looks sharp on your M1 Pro. The A18 Pro doesn't do that downscale: it only offers a HiDPI size when twice that size is a resolution the monitor itself runs at. On a 4K panel that leaves 1920x1080 HiDPI and nothing in between.

Smooth scaling works by adding those in-between sizes to macOS's list for the display, which is the password prompt and the flash you saw. The Neo refuses every one of them, so after the flash nothing new is there and the switch falls back to off. Other tools that use the same method get the same result on the Neo.

The part that's on me is that Crisp said nothing when that happened. In the next release the switch is greyed out on the Neo, with a line that says why, so you don't get the password prompt and the flash for nothing (#179).

The one workaround people report is a virtual display at 2560x1440 HiDPI mirrored to the monitor. I tried that route in Crisp too. It gave sharp 1440p, but it stuttered even on a much faster Mac, and it wasn't reliable enough to ship, so Crisp won't offer it for now. This issue closes when #179 is merged.