Back in August, Microsoft announced that it was working on bringing background effects to the Microsoft Teams web app. This week, Microsoft announced the public preview of this feature. With this feature, you can turn your video on with custom background in your Teams web meetings.
Microsoft also confirmed that not all GPUs are supported for this feature for now. If the feature does not appear in the meeting/call pre-join screen in your Teams browser experience, your GPU is not supported. Another limitation is that you need Edge or Chrome browser for this feature to work.