Microsoft has recently released an update to address the Teams flickering. I was able to confirm with a client who had the issue prior to the update.
Jason (see page 5) assisted me:
Hi
We had similar issue, when sharing applications over Microsoft teams. The upper menu bar will flickers if we use Share "Window" and does not flicker if we Share "Desktop"
A quick search found that Microsoft has recently released a patch that addresses this issue. Which we have just tested and confirmed it did fixed the screen flickering issue for window sharing in teams.
If you are using Windows 10 download KB4559003:
https://www.catalog.update.microsoft.com/Search.aspx?q=KB4559003
KB explain:
https://support.microsoft.com/en-au/help/4559003/windows-10-update-kb4559003
I hope this helps you too.
*we found out the above only applied to Windows 10 1809.
Regards
Jason
Hope that helps!