Thanks All. I got a response from Microsoft Teams Support:
Microsoft has reduced their bandwidth and quality settings to 720p or less in some cases with the surge of usage due to corona virus. Until they upgrade to meet demand or people go back to normal life we won't be able to really get solid video through the service for a bit
Refer : https://techcommunity.microsoft.com/t5/microsoft-teams/poor-videos-during-teams/m-p/1290304