My mouse cursor is super tiny in wayland applications. The scaling in swaybar and xwayland applications is correct though. On the screenshot you can see firefox-wayland (from nixos) but this also happens in other wayland applications such as eye-of-gnome or termite.
As suggested elsewhere I've already added dmz-black theme to ~/.icons/default, this only changed the cursor theme for swaybar though.
Sway Version: sway version da0ad4c39ed91c0d485b3d519ad1631ea6a46ba2
Configuration File:
output eDP-1 {
pos 0,0 res 1920x1080 scale 1.25
bg ~/static/pictures/wallpapers/subway.jpg stretch
}


There isn't (yet) a centralized, or standardized way to tell Wayland applications which xcursor theme (and at which size) they should be using.
What Sway does is set and export the environment variables XCURSOR_THEME and XCURSOR_SIZE. Some applications look at these (for example, swaybar). XWayland is a special case, handled by Sway.
firefox and gtk applications are probably using the gtk/gnome settings:
https://github.com/swaywm/sway/wiki/GTK-3-settings-on-Wayland
The gnome tweak tool does work in sway, if you are (or have to be) on ubuntu
sudo apt install gnome-tweak-tool
you can fix your appearance setting pretty quickly there, then hardcode them in config with the ^ above guides.
What happened me to was, I started gnome in wayland to help troubleshoot a zoom issue... it must have blew out all my gtk settings on first start... pretty frustrating.
Same problem here
This is a GTK bug. They should handle XCURSOR_THEME and XCURSOR_SIZE.