Check for the last restart time of your devicetype systeminfo in command prompt and check there or go to task manager see the performance of the device. restart teams and see.
it's not resolved, check user has proper license or not. If he had properly license opening web version and check whether it is running normally.
then we need to clear the cache memory of teams from %appdata%\microsoftteams in user computer and restart the teams app.
if it is not working normally ,then download teams app and sign in again.
3. Not able to share screen teams?
If you are not able to share screen in in meetings, then Meeting admin to change the who can present option to everyone.
screen sharing not working during chat then lower your screen resolution. test with different resolution and see which one is supported when screen sharing.
also not working, check for updates install updates of teams or your device OS.
4. Audio quality is not good in teams meeting?
open teamssettingsdevicesaudio devicesthere we can make audio settings according to our audio deviceand make a test call to verify it.