We could use some more info here:
Here's a general guide to this issue you might find helpful!
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-Model number SM-G975U
-Serial number <hidden>
-Software update information
Current version: G975USQS4DTF6 / G975UOYN4DTF6 / G975USQS4DTF6
Security patch level: July 1, 2020
-call screen , video call is grayed out
-just used Google duo