I have the same issue on Phone 2 and it drives me to the point where i wanna sell it and buy another brand (even though i don’t like to change my phone often)
The last battery low notification is at 10%, lower than that you’re on your own. No 5% warning, no 0% warning, nothing, just that Shutting down screen while in mid game. My old Xiaomi had a notification with a 30 seconds countdown and you had enough time to plug your charger before it shut down. And yes, the notification was shown even mid game, even with game mode and/or dnd mode on.