It might be pulling an audio format that either youtube resampled, or that ffmpeg had to resample when merging the video because it's not compatible with the video format.
There's a way to pick preferred audio and video formats it will choose over what's simply the best bitrate, but you'll have to look in the manual for more details.
Hmm... I listed available presets with `-F` option, and then downloaded various different presets (actually, examples have this nice option to download and merge all available audio presets `yt-dlp -f 'bv*+mergeall[vcodec=none]' --audio-multistreams `). All of them sound like from within a cartboard box when played in vlc, much worse than when I play it on youtube... This is very notable around 00:00:50 of the clip.
Maybe I misinterpret logs but I checked and I can't see anything that would suggest the audio is resampled
---edit---
Silly me. I had VLC audio effects enabled and that was resulting in song sounding different than on youtube. Sorry!
There's a way to pick preferred audio and video formats it will choose over what's simply the best bitrate, but you'll have to look in the manual for more details.