I have been having this flashing dot constantly, even when I am not on a phone call. I just noticed this earlier today and it's been non stop. So not sure why its flashing even though it's been stated that it only flashes when on calls.
It's the proximity sensor and is supposed to blink only while your on a call.
If it blocks when you're not on a call, restart your phone.
This worked for me. Good luck.
This happened to me many times. Most often when I use samsung wireless buds. Fun fact: did you know that you can't use use the dial pad on speakers when the proximity sensor is flashing. I feel like I have to restart the phone every now and then to avoid triggering the proximity sensor indefinitely.