@Leonardo Bezerra Silva Junior ,
To locate the log files, could you share with us the specific time when you receive messages in Teams client?
I tested in Ubuntu 20.04 with Microsoft Teams version 1.4.00.7556(64-bit). When message comes, the banner notification will show in the top of the desktop Window as below.
Above all, check if you enable banner notification in your client properly.
Then, try to clear your client cache as below:
rm -r ~/.config/Microsoft/Microsoft\ Teams\ -\ Insiders
If no luck, you could try to sign out your Teams client and re-sign in again to check if this feature is recovered.
If all the suggestions are no help, I want to confirm more question with you:
What changes do you do before this problem happened?
Does anyone else have the same problem?
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