Why can’t I play roblox while watching youtube?

So I use to be able to play roblox and watch youtube by making the youtube screen small and having it in the corner of my iphone while playing games on roblox. sometimes the game music would overlap my youtube audio so I would have to turn the game’s music off to be able to hear the music audio. Now anytime I join any game on roblox it doesn’t allow me to listen to my youtube video at all. My youtube video pauses automatically as soon as I begin playing a game. I’ve tried turning off the game audio but it doesn’t work. It should be noted that I switched iphones from an iphone 11 pro to a iphone 15 pro a couple of months ago and this might be the cause for this issue. But either way I need to know how to fix it!! Apple please help me or I’m switching to android.

[Edited by Moderator]