One complaint from new M1 Mac owners is that there doesn’t seem to be any way to enable 1440p Retina scaling on external monitors.
Apple has never officially supported this on sub-4K monitors, but there were workarounds for Intel Macs that don’t work with any of the M1 machines. Fortunately, there is now a solution …
MacWorld points to a third-party solution.
It’s called BetterDummy, and it essentially tricks macOS into thinking you’ve plugged in a 5K monitor. Using Apple’s display mirroring features, you can then reflect the fake monitor’s contents onto your real 1440p panel and enjoy all the advanced scaling options that Apple itself won’t provide. (The app is free with optional donations.)
I’ve tested BetterDummy myself on a pair of external 1440p monitors and can confirm it works as advertised.
The site’s Jared Newman does warn that the process isn’t exactly intuitive, but he provides a complete illustrated walk-through, which I recommend reading. He suggests trying 1920×1080 first (full HD), and then 2048×1152 if you want to show more content, or 1760×990 if you want high magnification.
He also adds a few other cautions:
Some users have reported problems with putting their MacBooks to sleep via a hot corner or by hitting Shift-Control-Esc, as the virtual screens will simply freeze in place instead of turning off. If this happens, head to the BetterDummy menu bar icon and select Settings > Disconnect and Reconnect on Sleep, but be warned that you may still run into sleep issues on rare occasions.
BetterDummy can also stop working when you unplug a monitor, plug in a new one, or connect an iPad to use with Sidecar. If this happens, click the BetterDummy menu bar icon, then disconnect and reconnect your Dummies under the Manage Dummies menu.
Finally, keep in mind that the option to automatically run BetterDummy at startup is off default. You can change this via the menu bar under Settings > Start at Login, but you’ll still have to enter your device password and wait a few moments before BetterDummy’s mirroring trickery kicks in.
Still, it does solve one of the few problems people have experienced when upgrading from Intel to M1 Macs.