I play Forza Street everyday and while I'm playing I usually listen to Spotify music and I have to lower the volume of the game from Xbox game bar every time I start the game. it's really annoying. I use the Xbox game bar beta and I launch it using Win button + G shortcut. Windows 10 insider fast ring build 18985
if you're an insider, try recreating this problem and adding it as diagnostic report to this feedback and upvote:
https://aka.ms/AA63z6d