What's your power profile set to?

Edit: check this comment

Seems a lot of people reference those tweaks to fixing audio issues generally.

Might check the kernel log to see if the kernel is emitting error messages that look relevant.

$ journalctl -krb

(will be in reverse order)

Or

$ sudo dmesg

EDIT: Might also check to see whether it still occurs if you plug headphones into your motherboard's headphones output and switch to using that as your output with pavucontrol or similar.

Kubuntu 25.04 here. Did you edit the audio quantum setting? If not, you should. It may or may not be the same issue, but I would get occasional buzzing when playing games. It turns out the default audio buffer time is really small, so when you're doing something CPU intensive (such as playing games), the CPU can't consistently fill out the buffer on time, leading to occasional audio hiccups. Increasing the audio buffer time will slightly (ie, imperceptibly) increase audio delay and will give the CPU more time to fill out the audio buffer, which solved the audio issue for me. Try putting this line:

context.properties = {default.clock.min-quantum} = 1024

into /etc/pipewire/pipewire.conf.d/pipewire.conf

(you may have to create some folders and files).

Then restart and see if that fixes anything