Why does my SIM card sometimes not get detected?

My ROG Phone 5 is experiencing issues where sometimes it does not detect the SIM card, and when it does, the signal is unstable with very weak connection.

However, strangely, when I try to open a game, the mobile data connection is very stable and has a good connection.

This is different from the usual problem of detached connectors at the back of the machine, because the SIM card is only occasionally unreadable, not completely unreadable and my Wi-Fi and fingerprint are working fine