1080p outright looks blurry after using 4k, so its pretty hard to even contemplate going back
Examples:
https://github.com/Tecate/bitmap-fonts
If you're on 4K you can simulate how they look on 1080p with 2x integer nearest neighbor scaling.
The by current standards normal sharpness is nice too (1080 screens aren't really blurry, they're pixely).
I basically went back to 1080p because of this.