How to disable the message "more than one device is trying to play music"

I know there are a lot of people asking the same question, more than one device is trying to play music and ask me to upgrade family plan. I used to have two accounts, but i've stopped using the old one and deleted the old account from all other devices as suggested by other answers. Now I only use the new one for my iPhone, iPad, mac, HomePod mini, apple tv... but still I will receive this message. (So even if I'm single with multiple devices, I need a family plan?)

This happens to me every time I drive home. I have my iPhone plugged in my car and playing music via CarPlay. and I have two HomePods with automation "play music when i arrive at home". Every time I approach my home CarPlay will stop and this message will show up in the Music app. This is annoying! I notice that in Home app, click HomePod mini, in MUSIC&PODCASTS primary users, there are "two" users, my account and a HomePod account. Could that be the reason I got the message? But I don't want to sign out my account, why should I sign out my account on my device?

I would appreciate it if someone offering some USEFUL information rather than copy and paste saying restart your device, check the devices with my apple id, balabala... I've already done that! I won't ask this question if I could find any useful steps online.

If this is a way apple music earning extra money..................... okay fine, I'll click "not now"