Does this issue persist all the time?
Does anyone else have the same problem in your organization?
I did a test in our new Teams client but it seems there is no issue when we share our screen in Teams meeting. As a workaround, it recommends you try to check if you could share screen normally in Teams Classic.
Meanwhile, if this issue only happened in specific user, you could also try to clear Teams client cache file to see if it can be fixed.
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