I though my board was damaged because my fan stopped working had to replace it, I was having unexpected reboot issues, external drives kept unmounting, and then I noticed that I had red bars on temperature graph that meant “throttling” and also saw a lightning bolt from time to time showing up on the upper right corner of the screen. So I connected the dots and bought an official raspberry pi 4 usb-c power supply. My raspi is now working great ( phew ).

Just wanted to share.