Any particular reason why you are wanting to use a Thunderbolt Display? DisplayPort, HDMI, and USB-C monitors will work too (USB-C to DisplayPort, USB-C to HDMI, HDMI to HDMI, HDMI to DisplayPort, or USB-C to USB-C).
A 1440p (109 ppi) screen is never a good deal on a modern Mac. Even for free. A new 27" 4K screen will be so much better and won't cost anything like as much as a 5K screen.
This isn't true. Many people use 27" 1440p displays and are happy with it. It's really a subjective thing and people have different preferences. Also, the further back you sit from your display, the less important having a HiDPI display is, as you cannot see the pixels from that distance.
This guy returned his 4K display and went back to 1440p since the non-integer scaling he used was bogging down his M1 Mac when other applications were pushing CPU/GPU.
Ideally, you want a monitor that has around 110ppi or 220ppi for the UI to not be too big or too small without having to do any scaling. This blog explains it some more.
If you’re considering an external display for your Mac, there’s a few important decisions to make. Apple doesn’t sell external displays any more, so you can’t just default to their wisdom. That’s an issue, because not all displays are well suited for Macs.
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