I booked an appointment for Samsung service centre to check what's wrong. However, they said they will need to replace the whole main board which cost around RM1800.

Decided to send to third party service centre. Upon calling the 3rd party SC, he explained that they have many Samsung phones from Note20 series until S22 series that encounters this issue. After I sent my phone to him to check, he said that is caused by faulty baseband IC. He needed to order the spare parts from China and the repair was only done today. So far not facing any issues and signal is great now.

Total repair cost is RM320.