I`ve been using opera GX for only a bit now but i use the built in audio since i dont want to waste ram on Spotify and its generaly more calm for reading and browsing but i have noticed that the audio calms down only after 30 seconds or so of you not being active and just sitting idle cuz you are reading something or else
i would like it more if this is set higher as i do read allot and i like the background music/audio