Hi TheOther_JC,
We appreciate you reaching out to us. We understand that the Repeat mode automatically turns back on.
We’d like to gather additional details that may help us be in a better position to assist you.
Are you experiencing this issue after choosing a playlist?
Are you launching the Music app through a widget or a shortcut?
In the meantime, we recommend that you check for a software update.
While it isn't inherently assured that an update will resolve the issue, updating to the latest software version for your device can help isolate potential software issues.
Kindly secure a backup and update.
How to back up your iPhone, iPad, and iPod touch
Update your iPhone, iPad, or iPod touch
Take care!