I found that if you have Ubuntu 25.04 and use gnome-tweaks to change the cursor theme from Yaru to one of the others that are provided, you will find none of them (except Yaru) work when selected. It’s because cursor themes need to have a default cursor defined or they will not work in 25.04.
You can fix this by adding a symbolic link named default with target left_ptr inside the cursors folder of the theme you want.
Example: Make DMZ-White work as your cursor theme.
Open the terminal and enter these commands:
cd /usr/share/icons/DMZ-White/cursors
sudo ln -s left_ptr default
DMZ-White should now work when selected. Bonus: DMZ-White is one of the few cursor themes other than Yaru that works in Firefox Snap.
In fact, for any cursor to work in Firefox Snap and other Snaps (except VLC, which is a special case), it is necessary that the cursor is in a theme Snap that connects to Firefox, either automatically or manually.
For example, the flugir-budgie-theme Snap has the Bibata and GoogleDot cursors, and if you download that Snap, it will allow you to use those cursors in Firefox as well.
I tried changing the cursor theme and it seems that all the themes work well on firefox snap too. What do you mean by ‘they don’t work’?
I use Ubuntu 25.04 with Intel GPU.
Fresh install from release ISO.
Without the fix, when you select one (other than Yaru) in gnome-tweaks, the cursor does not change. I am sure about that. Maybe this depends on the environment - My 25.04 uses Wayland and is a virtual machine. Either of those facts may be a factor. What about yours?
I actually did wonder if using Xorg would make a difference, however I did not test using the Xorg session as it is not possible to start the Xorg session in a QEMU/KVM virtual machine (it just returns to the login screen).
Anyway, the fix I gave works in my system. Also, I had read about this problem someplace months ago, so I did not invent the solution.