1- Trouble was present before installing Sonoma. I was hopping Sonoma will correct the problem.
2- When I am in Safari or Finder in full screen mode, I move my mouse in the top of the screen and in the normal behavior the three dots are suppose to pop-up. You can view what I call normal behavior here https://youtu.be/ucZHgUYuip8 and here https://youtu.be/6cMN6L_Nwyw
3- At this time, when I move my mouse over the top off the screen, the three dot are not poping up. You can view it here https://youtu.be/TuR2We_u-Pc
4- I have two user account on my Mac. In account number 1, the problem is here. In account number 2, everything work well
5- Safe mode did not solve the issue but if I boot in safe mode in account number 1, keep it open and log to account number 2 and open safari. Then after I log off from account number 2 and go back to account number 1, everything work well in safari but not in finder !
6- I just try the same step in regular boot mode and the issue is solved too in safari and not in finder !
7- I try again the same step but this time I open Finder in account number 2 and when I am back to account number 1, issue is solved for Finder too (regular boot mode)
In summary, if I boot in regular mode I have issue with the three dots. But if I log to a second user account, open safari and finder, log off from the second user account and back to the first one, everything work well
Hope it give you some clues