That's probably because Ubuntu 21.04 used Wayland by default for all but Nvidia [0] and 22.04 enabled it for Nvidia [1], and Wayland's fractional scaling is an ugly hack (both in how it's implemented and how it looks) [2][3]. Progress is being made [4], but it's quite slow.
Switch to the X session on the login screen and you should have good scaling again (also, lots of applications that do screen sharing, like Zoom, do not work on Wayland [5]). Or just be like me and use Mint, which has no plans for Wayland support and you don't have to think about any of this.
Thanks, good to know it's only due to Wayland, and that it's both being worked on there, and that there is a quick fix otherwise when I upgrade to 22.04.
Switch to the X session on the login screen and you should have good scaling again (also, lots of applications that do screen sharing, like Zoom, do not work on Wayland [5]). Or just be like me and use Mint, which has no plans for Wayland support and you don't have to think about any of this.
[0]: https://www.omgubuntu.co.uk/2021/01/ubuntu-21-04-will-use-wa...
[1]: https://www.phoronix.com/scan.php?page=news_item&px=Ubuntu-2...
[2]: https://www.reddit.com/r/kde/comments/lficfe/wayland_fractio...
[3]: https://gitlab.freedesktop.org/wayland/wayland-protocols/-/i...
[4]: https://gitlab.freedesktop.org/wayland/wayland-protocols/-/m...
[5]: https://community.zoom.com/t5/Meetings/Wayland-screen-sharin...