As described in this AskUbuntu post, basically every time there’s some audio playback, there is a variable delay when the audio starts. It can range from anything like a fraction of a second to a full two seconds.
I noticed this first when playing YouTube videos and then it was excruciatingly obvious and a real problem while editing audio in Audacity.
If it’s any good, I’m using an NVIDIA RTX 3070 and I’m still under X, not Wayland, and using Pulse Audio.
My audio is going to my HDMI connected monitor where my speakers are connected.
This is only happening since I did a fresh install of Kubuntu 24.04 earlier this September.
Update: Added my graphics card model.
I’ll be interested to know if you manage to fix this, I had this issue and nothing I tried worked. Setting the audio decides not to suspend would work but only for a single audio source. The closest I got to fixing it was to use the inbuilt sine wave function to play a constant 20Hz sine wave which I couldn’t hear but stopped the playback device from suspending. But that started to cause its own issues so I just got an audio extension lead and switched to using my front panel audio