Two years ago, a feature was added to Android 12 where the previous audio source would fade out when a different source starts playing (e.g. you start a YouTube video while music is playing).

A post was made on XDA on 18 May, 2021:

Audio focus is determined by the app in question that's playing media. Google explained that when an app requests audio focus while another app has the focus and is playing, the framework forces the playing app to fade out. This will be a nice change because instead of another app abruptly ending its audio stream whenever the user starts another session, Android 12 will nicely fade out the old stream that's lost focus.

I remember being very impressed with this feature and found it satisfying every time. However, after buying a Samsung Galaxy A24 running Android 13, I was disappointed to discover that this feature is missing.

This is yet another reason why I can't wait to install a custom ROM on this phone. For now, though, I guess I'll just have to wait.